Rear door lock?

[David in NC]

One of the rear door latches on my son's '97 XLT won't work if you try to open the door when it's locked. After trying and failing, it won't open from the inside even after it is unlocked. The only way to open the door is from the outside. If you unlock the door first, the latch works fine. We have replaced the inside latch with a Ford latch. Any suggestions? Thanks.

 

[David in NC]

Actually we replaced the plastic inside handle, not the latch. The front latches open the doors even when they are locked, but the back don't. Any ideas?