I have an 1995 E420 that has developed a problem with the driver's door lock.

The only problem is that the driver's door will not actually lock. ALL other functions work correctly. This includes locking/unlocking all other doors using the driver's key and/or push button. Additionally, the driver's push button is raised or lowered correctly when any of the locks are activated with the key. But even though the push button is in the lower position, the door itself is not locked. I would have thought that if there was a problem with the driver's door lock that the push button would not operate correctly.

Any ideas?