Cannot program 2nd keyfob

I just purchased a 1998 GMC Sierra extended cab with keyless remote entry. The keyfob I have is numberd 16245100-29 and it works correctly. I purchased another one on Ebay(the exact same number) and followed the directions for programming both keyfobs. My system uses the 4 to 8 pin jumper on the dlc. Both keyfobs will work but not at the same time. It will not allow a second one to be programmed. I have tried repeatedly and the first one programs great but when I try the second one, immedieatly after the first one, nothing happens. According to the directions I should be able to program up to 4 remotes one after the other as long as 60 seconds does not pass between programming each of them.

Any ideas or suggestions will be greatly appreciated

Come on people, surely someone has heard this one before....

NEED help....