Chevy key FOB issue

[bobbytheboozer]

2006 Chevy 2500hd. I had issues with my original key fob about 6 months ago and bought a 2 pack of new key fobs off of Amazon. I reprogrammed them and the new ones worked fine. Yesterday morning I noticed that the unlock button on the new fob I was using didn't work anymore. I grabbed the other new key fob and reprogrammed that fob and I still can't unlock my truck. The lock and panic alarm buttons work fine. The original key fob is toast.

Is this an issue with my truck? Does anyone have any idea what might be wrong? Thanks in advance.