190E Malfunction Unlocking Drivers Door

[Jim Herold]

1. Problem: The driver's side door will not UNLOCK itself or actuate the central system using the key. When the key is turned, the window button tries to lift, but cannot. Nothing happens after that.
2. The drivers door operates properly to LOCK itself and operate the central system.
3. The door locks and unlocks itself and operates the central system when the "button" is pulled or pushed from the inside.
4. The drivers door locks and unlocks when a key is used in the passenger door or trunk.

Replacing the door element did not fix the problem. Lubrication of the moving parts did not help.

What would prevent just the UNLOCKING operation using the key on just that one door?

Thank you for your help.