Door lock problem

This ladies car does this---- When she activates the remote opener the door locks open as normal. Then when she opens (lifts) the driver's side door handle the door lock knob or link drops down into the lock position not allowing her to open the door.

The power solonoid seems to work fine for the lock. Does anyone think this is the fault, or possibly a bad door latch assembly? Something seems weak or has worn out to me here. Any ideas would be appreciated.

1999 Mercury Tracer

Surprised nobodys run across this one before. Did the job today and it turned out to be a bad latch. Springs were all intact, but a plastic cam wore out and allowed the button rod to fall when the door handle was lifted.

The dealer wanted $392.92 new for this part.
I pulled a used one off of a '98 Escort at a local junk yard for $3.50
Works great. Relatively easy job.
Seems like a common problem on these Tracers and Escort