Jvc kd-dv 7404 ...when i play a dvd videos...sounds comes but Video doesnt disply on my jvc screen.....but when i play a MP3 dvd ...the Folder manu display on my screen...so what's problem when i play a Movie Of dvd....?....no Disply on Screen

That is because you have a parking brake safety wire connected. You can bypass it by finding the wire on back of your radio, disconnect it from the parking brake ground and reconnect it to the radios ground at the wiring harness. this will tell your radio that your car is always in park.