Door locks
 

I have a 2001 2500 hd only drivers door locks and unlocks with key fob or switch in drivers door. If you lock all the doors manually the fob will unlock but not lock. Vehicle was recently stolen and work fine before. The fob will set alarm and turn it off.

You may have better results posting that question here: https://chevroletforum.com/forum/1999-2006-gmt800-108/
That's a sub-forum for your year of truck. Hope you get it sorted out, and the thief gets strung up by his jelly beans.