Key fob wont lock doors

[Nevyard]

Hi, i created this account just to ask this question. From everything ive read i havent found anyone else with my exact problem, just similar. I have a 1998 silverado k2500 diesel with an OEM key fob that worked perfectly at one time. The key fob will unlock the doors just fine but it will not lock the doors. When i press lock on the fob nothing happens but when i press it a second time it beeps the horn as if it set the alarm is set, but it isnt and the doors arent locked. If it makes any difference, my security light is on in the dash at all times because i have a tuned ecm- i also specified in my tune to have the vehicle anti theft disabled. Also both of my doors are from 2 different trucks (that both had electric locks oem) so i dont know if theres some kind of anti theft in the doors themselves? It seems like i lost the ability to lock with the key fob after swapping the doors. Any help is much appreciated thanks.

 

[MatSLO]

Perhaps your keyfob just needs replacing...

 

[Nevyard]

Perhaps your keyfob just needs replacing...

I have replaced it. After programming the new one it does the exact same thing