Keyless Entry On Driver's Side Won't Work

[greggr]

The keyless entry on my 2008 Sierra won't lock or unlock the driver's side; the passenger side works fine. Tried the other remote, which is new, and get the same result. The power lock on the driver's armrest also won't lock or unlock the door, the only way to lock/unlock the door is with the key or manually with lock knob.

 

Greatly appreciate any suggestions on what to try.