I just bought a new remote key fob for my 1999 Silverado. I followed the procedures of pressing and holding the unlock button on the door while turning the key to ON, OFF, ON, OFF, then releasing the unlock button on the door to activate the programming. However, the doors do not lock and unlock when I release the unlock button on the door to confirm programming mode. I continued by holding both the lock and unlock buttons on the remote, with no luck. Since the doors do not lock and unlock at the door, I'm thinking the problem is not the key fob but the programming on the door. Has anyone gone through this and how did you resolve it to program the new remote fobs? Thanks. -Joe