Make sure you have the right remote for your application. There are alot of remotes that 'look' the same but what counts are the GM/LEAR# and also the FCC ID#.
I would suggest you take your VIN# to your dealer and see if they will give you the correct numbers for your vehicle. You then can purchase the remote off of Ebay for somewhere around $10. Then try to reprogram.
Good Luck,
-slacker