ZX5 Rear Door Lock on 2004 Ford Focus

I have a Ford Focus that I notice that when the car is locked.. All doors lock bu the rear passenger door.. It seems jammed and won't let me lock it manually..
Any help? or a possible cost to fix this..
They are Automatic locks, Keyless entry
Please anyone :)

Asked by for the 2004 Ford Focus
Sounds like you may have a bad door lock actuator. I believe the latch adn actuator come together as an assembly. Check to make sure the rear door in question is adjusted to close properly, improper adjustment can also impede the actuator operation. Good luck.
I have the same problem, but now it is with both back doors. Is this common with the Ford Focus.
1 more answer
I had same problem-my Focus has "child proof" lock option that can be switched on and off with the ignition key. If you have your owner's manual, it explains how to to this-solved this problem for me.