The codes I have won't work for my Sylvania TV

Are you using these codes 011, 012, 003, 073,041......???? you can try and do it this way also,
Follow these steps to program the remote control. check out this link:
http://esupport.sony.com/perl/model-remote.pl?mdl=RMV302#instr

http://www.docs.sony.com/release/RMV302codes.pdf

1. Turn on the component to be programmed.
2. On the remote control, press and hold the SET button.
3. While holding the SET button, press and release the POWER button
4. Release the SET button.
5. Press the appropriate component button for the component being set up.
6. Using the number pad, enter the component's manufacturer code. NOTE: If more than one code number is listed for the manufacturer, repeat the procedure, entering one code at a time until you find one that works.
   
7. Press the ENT button.
8. Point the remote control at the component.
9. Press the POWER button to verify operation.

• If a new code number is entered, the code number previously entered will be erased.
• When the batteries are replaced, the programmed codes may be erased. It may be necessary to reprogram the remote after replacing the batteries.
• The operation of a combination deck of any kind is not guaranteed.
• Some product functions may not be able to be controlled by the remote control. Use the remote control provided with the component.
• If none of the codes listed for the manufacturer work, it may be necessary to try codes listed for other manufacturers or perform a search for the correct code. Consult the Operating Instructions provided with the remote control for steps on searching for the correct code.
• In some rare cases, you may not be able to operate your non-Sony equipment with the supplied remote control. This is because your equipment may use a code that is not provided with this remote control. In this case, please use the equipment's own remote control.