AS I recall it, you have to program all 3 fobs at the same time; can't do just the new ones. Don't know if this solves your problem, but check on this before doing the programming.

 

problem is new ones wont program. When I was done with programming my old one still worked but neither of the 2 new ones worked

 

When you release the unlock button, did the doors unlock and lock on their own?

Step 1: Sit in the vehicle with all the doors closed and unlocked. Insert the key into the ignition. Do not turn the key until directed.

Step 2: Press and hold the Unlock button on the driver's side door. You will hear the locks make two clunking noises, indicating they have completed an unlock/lock cycle. Continue to hold down the Unlock button.

Step 3: While holding down the Unlock button, turn the key to the accessory power position then back to the off position. Repeat turning the key from the accessory power position to the off position for a total of two cycles.

Step 4: Release the Unlock button. Your Silverado will automatically cycle the locks as it did in Step 2.

Step 5: Simultaneously hold down the Lock and Unlock buttons on your fob for 15 seconds.

Step 6: Program any additional remotes for repeating Step 6 for each remote. Up to four remotes can be programmed.

Step 7: Exit programming mode by starting your Silverado. Turn off the vehicle and test your remotes.

 

http://www.dieselplace.com/forum/76-speciality-forums/81-electrical/473837-key-fob.html

 

Are they the correct key fobs? I just got my truck from a small dealer and they gave me a key fob that is for another vehicle. So I had to find out the correct part number and just ordered a new one.

 

I had problems programming the second FOB I bought with my used truck. Turned out I was not cycling the key fast enough. It's on-off, as quick as you can turn it. Not on..........off. Speeding up made the rest of the instructions work fine for me. Now both FOBs work correctly. (Yes, I had to re-program the original one at the same time).

 

Yes I got into the program mode. I will check tomorrow, Maybe its as simple as the wrong remote.