Key Fob not working

[BigOh!]

I have a 2k2 Denali just purchased. Didnt came with fobs So I got one on ebay
http://www.ebay.com/itm/121326756441?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Try programming it to no luck. Follow the OEM instructions. I get to where the locks lock and unlock and you have to press the unlock and unlock on the fob and after holding them for forever nothing happens.

Any Ideas?

 

[criffaaa1]

Got mine off eBay too, used this vid, it took all of 5 min for 2 fobs.

How to Program a GM Keyless Entry Remote Key Fob …: http://youtu.be/yZtekZylVVg