Focus rear door won't open from outside?

I have a 2000 Zetec Focus and the rear off side passenger door won't open from the outside, from inside is ok but annoying. I have had the door panel off, but cannot see anything broken or untoward. What is the link between the external handle and the locking mechanism as there doesn't seem to be anything connecting the two, or am I missing something obvious. Your help please.

Garry C
January 2009