Driver's Door Won't Lock

I have a '99 Oldsmobile Bravada and my driver's door will not lock when I either press the lock button on the door or on the keyless remote. I can lock the door if I manually push down the lock so I am at least locked up.

The lock looks like it tries to move down a little bit but wont. So I opened up the door panel to check it out and see if something was blocking it and there was nothing. When I lock the door manually there is no feeling of extra pressure needed. So at this point I am stumped.

Any one have any advice or ideas?

Did you check to see that the actuator was plugged in? If it is, the actuator needs to be tested as it might be bad.

Where is the actuator located? In the door panel I assume but what part?

I found one of mine sticking once. I looked at the end of the door where the latching stuff is and when I worked the manual knob up & down, I saw a lever working inside the latching stuff. I gave it a good shot of penetrating oil while working the manual knob and it got easier to work. Soon the electrics started working like new.