Problem with the keyless entry

Ok, I have a 1999 jeep grand cherokee. It came
with the factory keyless entry (key fob). The other
day the key fob stopped working and I have to
use the key now to lock or unlock the drivers
door. (Its the only door that has a keyed lock).
Anyway, I went to a local auto parts store thinking
the key fob had a weak or a dead battery. They
changed the batterys in both remotes, ($15.00)
however the remotes still did not work. So I called
a lock Smith who came out and attempted to
reprogram the system .... Thinking that was the
issue. ($125.00) He said that the remotes were
working as they are intended, and showed me on
his (screen) that the vehicle and remotes were
working. However the doors still would not
unlock or lock using the remotes. Thinking that
the receiver in the passenger door was bad I
replaced it. ($400.00). The doors still will not lock
or unlock using the remotes. Now here is my
thinking. When I called the lock Smith he showed
me that the vehicle and remotes were
communicating with oneanouther. So I didn't
need to go purchase a new receiver, but I did. I
then took the jeep to the dealership ($75.00)
thinking they might be able to get the problem
sorted out. They had no luck in getting the
remotes to unlock or lock the doors.  So my
question now is what would be keeping the doors
from working with the remotes? The remotes
work. The remotes are communicating with the
jeep but the jeep doors still will not lock or unlock
with the remotes. The over head console shows
"lock/unlock, horn sounds, lights flash" for the
remote and everything is turned on. I'm stumped!
Any help solving this problem would be greatly
welcome.