My latch wouldn't catch the door.
It was a sticky latch mechanism.
The cable wasn't allowed to move freely since 
the sliding mechanism in the latch didn't move.
The latch was greased up but the grease was dirty and
stiff from cold.  A little WD 40 and
the whole door latches and unlatches easily.
Just take off the door panel and spray the rail and
latch insides.