I try to install the tv tuner that designed to windows vista 32-bit but my laptop has a vista premium 64-bit. why it's not working?

Most programs designed for the 32-bit version of Windows will work on the 64-bit version of Windows. Notable exceptions are many antivirus programs.
Device drivers designed for 32-bit versions of Windows won't work on computers running a 64-bit version of Windows. If you're trying to install a printer or other device that only has 32-bit drivers available, it won't work correctly on a 64-bit version of Windows.

Windows 7 64bit does run programs that will run on windows 7 32bit, see here

How Windows 7 / Vista 64 Support 32 bit Applications

BUT not ALL 32bit programs will run on Windows 7!!! There are many programs that will run on Windows XP and before that will not run on Windows 7. IF you had Windows 7 Pro version (or upgrade) there is a program you can download from Microsoft that will simulate an XP environment to allow programs to run called "XP MODE".
Try to install the 32bit software first. If installation not succeed, it would be better if you first look into a newer version of the program you want to run.You have to consider that a newer version of your program might not be that much more expensive than upgrading to pro, and with the newer version, usually comes newer features.

Hope this help and if helpful RATE please.

HP Print Diagnostic Utility was created to help users troubleshoot and correct many common problems on Windows-based computers that can prevent printing.Follow the on-screen instructions to run the utility. Details and specifications File name: HPPDU.exe [1/1, 1.54M] System requirements: No additional prerequisites Released: 2010-08-13 Version: 3.0.0.013 Compatibility: Microsoft Windows Vista, Microsoft Windows Vista Home Premium (32-bit), Microsoft Windows Vista Home Basic (32-bit), Microsoft Windows Vista Business (32-bit), Microsoft Windows Vista Ultimate (32-bit), Microsoft Windows 7 (32-bit), Microsoft Windows 7 Home Basic (32-bit), Microsoft Windows 7 Home Premium (32-bit), Microsoft Windows 7 Professional (32-bit), Microsoft Windows 7 Enterprise (32-bit), Microsoft Windows 7 Ultimate (32-bit), Microsoft Windows 7 Home Basic (64-bit), Microsoft Windows 7 Home Premium (64-bit), Microsoft Windows 7 Professional (64-bit), Microsoft Windows 7 Enterprise (64-bit), Microsoft Windows 7 Ultimate (64-bit), Microsoft Windows 7 (64-bit), Microsoft Windows Vista (64-bit), Microsoft Windows Vista Home Basic (64-bit), Microsoft Windows Vista Home Premium (64-bit), Microsoft Windows Vista Business (64-bit), Microsoft Windows Vista Enterprise (64-bit), Microsoft Windows Vista Enterprise (32-bit), Microsoft Windows XP Fix/Enhancement: This version of the HP Print Diagnostic Utility provides an improved user interface in multiple languages, improved diagnostic and problem resolution capability, and support for usb and network connected devices.

HP Print Diagnostic Utility was created to help users troubleshoot and correct many common problems on Windows-based computers that can prevent printing.Follow the on-screen instructions to run the utility.

Details and specifications

File name:HPPDU.exe [1/1, 1.54M]System requirements:No additional prerequisitesReleased:2010-08-13Version:3.0.0.013Compatibility:Microsoft Windows Vista, Microsoft Windows Vista Home Premium (32-bit), Microsoft Windows Vista Home Basic (32-bit), Microsoft Windows Vista Business (32-bit), Microsoft Windows Vista Ultimate (32-bit), Microsoft Windows 7 (32-bit), Microsoft Windows 7 Home Basic (32-bit), Microsoft Windows 7 Home Premium (32-bit), Microsoft Windows 7 Professional (32-bit), Microsoft Windows 7 Enterprise (32-bit), Microsoft Windows 7 Ultimate (32-bit), Microsoft Windows 7 Home Basic (64-bit), Microsoft Windows 7 Home Premium (64-bit), Microsoft Windows 7 Professional (64-bit), Microsoft Windows 7 Enterprise (64-bit), Microsoft Windows 7 Ultimate (64-bit), Microsoft Windows 7 (64-bit), Microsoft Windows Vista (64-bit), Microsoft Windows Vista Home Basic (64-bit), Microsoft Windows Vista Home Premium (64-bit), Microsoft Windows Vista Business (64-bit), Microsoft Windows Vista Enterprise (64-bit), Microsoft Windows Vista Enterprise (32-bit), Microsoft Windows XPFix/Enhancement:This version of the HP Print Diagnostic Utility provides an improved user interface in multiple languages, improved diagnostic and problem resolution capability, and support for usb and network connected devices.

TRY HP Print Diagnostic Utility was created to help users troubleshoot and correct many common problems on Windows-based computers that can prevent printing.Follow the on-screen instructions to run the utility. Details and specifications File name: HPPDU.exe [1/1, 1.54M] System requirements: No additional prerequisites Released: 2010-08-13 Version: 3.0.0.013 Compatibility: Microsoft Windows Vista, Microsoft Windows Vista Home Premium (32-bit), Microsoft Windows Vista Home Basic (32-bit), Microsoft Windows Vista Business (32-bit), Microsoft Windows Vista Ultimate (32-bit), Microsoft Windows 7 (32-bit), Microsoft Windows 7 Home Basic (32-bit), Microsoft Windows 7 Home Premium (32-bit), Microsoft Windows 7 Professional (32-bit), Microsoft Windows 7 Enterprise (32-bit), Microsoft Windows 7 Ultimate (32-bit), Microsoft Windows 7 Home Basic (64-bit), Microsoft Windows 7 Home Premium (64-bit), Microsoft Windows 7 Professional (64-bit), Microsoft Windows 7 Enterprise (64-bit), Microsoft Windows 7 Ultimate (64-bit), Microsoft Windows 7 (64-bit), Microsoft Windows Vista (64-bit), Microsoft Windows Vista Home Basic (64-bit), Microsoft Windows Vista Home Premium (64-bit), Microsoft Windows Vista Business (64-bit), Microsoft Windows Vista Enterprise (64-bit), Microsoft Windows Vista Enterprise (32-bit), Microsoft Windows XP Fix/Enhancement: This version of the HP Print Diagnostic Utility provides an improved user interface in multiple languages, improved diagnostic and problem resolution capability, and support for usb and network connected devices.

Try HP Print Diagnostic Utility was created to help users troubleshoot and correct many common problems on Windows-based computers that can prevent printing.Follow the on-screen instructions to run the utility. Details and specifications File name: HPPDU.exe [1/1, 1.54M] System requirements: No additional prerequisites Released: 2010-08-13 Version: 3.0.0.013 Compatibility: Microsoft Windows Vista, Microsoft Windows Vista Home Premium (32-bit), Microsoft Windows Vista Home Basic (32-bit), Microsoft Windows Vista Business (32-bit), Microsoft Windows Vista Ultimate (32-bit), Microsoft Windows 7 (32-bit), Microsoft Windows 7 Home Basic (32-bit), Microsoft Windows 7 Home Premium (32-bit), Microsoft Windows 7 Professional (32-bit), Microsoft Windows 7 Enterprise (32-bit), Microsoft Windows 7 Ultimate (32-bit), Microsoft Windows 7 Home Basic (64-bit), Microsoft Windows 7 Home Premium (64-bit), Microsoft Windows 7 Professional (64-bit), Microsoft Windows 7 Enterprise (64-bit), Microsoft Windows 7 Ultimate (64-bit), Microsoft Windows 7 (64-bit), Microsoft Windows Vista (64-bit), Microsoft Windows Vista Home Basic (64-bit), Microsoft Windows Vista Home Premium (64-bit), Microsoft Windows Vista Business (64-bit), Microsoft Windows Vista Enterprise (64-bit), Microsoft Windows Vista Enterprise (32-bit), Microsoft Windows XP Fix/Enhancement: This version of the HP Print Diagnostic Utility provides an improved user interface in multiple languages, improved diagnostic and problem resolution capability, and support for usb and network connected devices.

HP Print Diagnostic Utility was created to help users troubleshoot and correct many common problems on Windows-based computers that can prevent printing.Follow the on-screen instructions to run the utility. Details and specifications File name: HPPDU.exe [1/1, 1.54M] System requirements: No additional prerequisites Released: 2010-08-13 Version: 3.0.0.013 Compatibility: Microsoft Windows Vista, Microsoft Windows Vista Home Premium (32-bit), Microsoft Windows Vista Home Basic (32-bit), Microsoft Windows Vista Business (32-bit), Microsoft Windows Vista Ultimate (32-bit), Microsoft Windows 7 (32-bit), Microsoft Windows 7 Home Basic (32-bit), Microsoft Windows 7 Home Premium (32-bit), Microsoft Windows 7 Professional (32-bit), Microsoft Windows 7 Enterprise (32-bit), Microsoft Windows 7 Ultimate (32-bit), Microsoft Windows 7 Home Basic (64-bit), Microsoft Windows 7 Home Premium (64-bit), Microsoft Windows 7 Professional (64-bit), Microsoft Windows 7 Enterprise (64-bit), Microsoft Windows 7 Ultimate (64-bit), Microsoft Windows 7 (64-bit), Microsoft Windows Vista (64-bit), Microsoft Windows Vista Home Basic (64-bit), Microsoft Windows Vista Home Premium (64-bit), Microsoft Windows Vista Business (64-bit), Microsoft Windows Vista Enterprise (64-bit), Microsoft Windows Vista Enterprise (32-bit), Microsoft Windows XP Fix/Enhancement: This version of the HP Print Diagnostic Utility provides an improved user interface in multiple languages, improved diagnostic and problem resolution capability, and support for usb and network connected devices.

HP Print Diagnostic Utility was created to help users troubleshoot and correct many common problems on Windows-based computers that can prevent printing.Follow the on-screen instructions to run the utility. Details and specifications File name: HPPDU.exe [1/1, 1.54M] System requirements: No additional prerequisites Released: 2010-08-13 Version: 3.0.0.013 Compatibility: Microsoft Windows Vista, Microsoft Windows Vista Home Premium (32-bit), Microsoft Windows Vista Home Basic (32-bit), Microsoft Windows Vista Business (32-bit), Microsoft Windows Vista Ultimate (32-bit), Microsoft Windows 7 (32-bit), Microsoft Windows 7 Home Basic (32-bit), Microsoft Windows 7 Home Premium (32-bit), Microsoft Windows 7 Professional (32-bit), Microsoft Windows 7 Enterprise (32-bit), Microsoft Windows 7 Ultimate (32-bit), Microsoft Windows 7 Home Basic (64-bit), Microsoft Windows 7 Home Premium (64-bit), Microsoft Windows 7 Professional (64-bit), Microsoft Windows 7 Enterprise (64-bit), Microsoft Windows 7 Ultimate (64-bit), Microsoft Windows 7 (64-bit), Microsoft Windows Vista (64-bit), Microsoft Windows Vista Home Basic (64-bit), Microsoft Windows Vista Home Premium (64-bit), Microsoft Windows Vista Business (64-bit), Microsoft Windows Vista Enterprise (64-bit), Microsoft Windows Vista Enterprise (32-bit), Microsoft Windows XP Fix/Enhancement: This version of the HP Print Diagnostic Utility provides an improved user interface in multiple languages, improved diagnostic and problem resolution capability, and support for usb and network connected devices.

File name: HPPDU.exe [1/1, 1.54M] System requirements: No additional prerequisites Released: 2010-08-13 Version: 3.0.0.013 Compatibility: Microsoft Windows Vista, Microsoft Windows Vista Home Premium (32-bit), Microsoft Windows Vista Home Basic (32-bit), Microsoft Windows Vista Business (32-bit), Microsoft Windows Vista Ultimate (32-bit), Microsoft Windows 7 (32-bit), Microsoft Windows 7 Home Basic (32-bit), Microsoft Windows 7 Home Premium (32-bit), Microsoft Windows 7 Professional (32-bit), Microsoft Windows 7 Enterprise (32-bit), Microsoft Windows 7 Ultimate (32-bit), Microsoft Windows 7 Home Basic (64-bit), Microsoft Windows 7 Home Premium (64-bit), Microsoft Windows 7 Professional (64-bit), Microsoft Windows 7 Enterprise (64-bit), Microsoft Windows 7 Ultimate (64-bit), Microsoft Windows 7 (64-bit), Microsoft Windows Vista (64-bit), Microsoft Windows Vista Home Basic (64-bit), Microsoft Windows Vista Home Premium (64-bit), Microsoft Windows Vista Business (64-bit), Microsoft Windows Vista Enterprise (64-bit), Microsoft Windows Vista Enterprise (32-bit), Microsoft Windows XP Fix/Enhancement: This version of the HP Print Diagnostic Utility provides an improved user interface in multiple languages, improved diagnostic and problem resolution capability, and support for usb and network connected devices.

HP Print Diagnostic Utility was created to help users troubleshoot and correct many common problems on Windows-based computers that can prevent printing.Follow the on-screen instructions to run the utility. Details and specifications File name: HPPDU.exe [1/1, 1.54M] System requirements: No additional prerequisites Released: 2010-08-13 Version: 3.0.0.013 Compatibility: Microsoft Windows Vista, Microsoft Windows Vista Home Premium (32-bit), Microsoft Windows Vista Home Basic (32-bit), Microsoft Windows Vista Business (32-bit), Microsoft Windows Vista Ultimate (32-bit), Microsoft Windows 7 (32-bit), Microsoft Windows 7 Home Basic (32-bit), Microsoft Windows 7 Home Premium (32-bit), Microsoft Windows 7 Professional (32-bit), Microsoft Windows 7 Enterprise (32-bit), Microsoft Windows 7 Ultimate (32-bit), Microsoft Windows 7 Home Basic (64-bit), Microsoft Windows 7 Home Premium (64-bit), Microsoft Windows 7 Professional (64-bit), Microsoft Windows 7 Enterprise (64-bit), Microsoft Windows 7 Ultimate (64-bit), Microsoft Windows 7 (64-bit), Microsoft Windows Vista (64-bit), Microsoft Windows Vista Home Basic (64-bit), Microsoft Windows Vista Home Premium (64-bit), Microsoft Windows Vista Business (64-bit), Microsoft Windows Vista Enterprise (64-bit), Microsoft Windows Vista Enterprise (32-bit), Microsoft Windows XP Fix/Enhancement: This version of the HP Print Diagnostic Utility provides an improved user interface in multiple languages, improved diagnostic and problem resolution capability, and support for usb and network connected devices.

Well you have answered your own question almost.  Here is what you do.  Go to the manufacture of the tuner and request a version of the driver and software for vista 64bit.