Laguna II central locking problem?

Laguna II 52 reg

My drivers door only locks but it will not unlock so i have to manually unlock it through the rear drivers door?

it has not long happened, ive tried another lock but that still does the same. im not sure if this is a common thing but its becoming a pain.

I have tested the wiring from the door plug and the plug onto the lock all seem to get good resistance.

Help will be appreciated before i start stripping the wiring out.

Kevin Colton