Are you using a relay circuit to switch the foglamps on and off?
If you are trying to run the foglights directly off the same circuit as the radio, you will not have enough amperage.

To diagnose the problem, use the fuse box diagram that is mounted to the inside of the fuse panel cover. Inspect the fuses for each system (sunroof, stereo, etc) that is not working. Report back with your findings.

And no matter what DO NOT INSTALL A HIGHER AMPERAGE FUSE to replace the blown fuses. If you install a 15 amp fuse in a 10 amp circuit, you risk an electrical fire that will destroy the car.