Central locking puzzle

[Baz1a]

Hi, my 75 has had the common problem of a failed driver's door latch/actuator with all other doors lock/unlock with central locking. I replaced the driver's actuator unit today with a brand new one from Rimmers, however, now the central locking has stopped working altogether. Fortunately I hadn't put the door card back. I then disconnected the multi connector socket from the new latch and all other doors work fine again.
Now the puzzle, when I connect the old unit up again (hanging free, just on the wires) , nothing works until I disconnect it. Before taking the old one out, it still worked the other 3 doors but just like the new one nothing works with it connected. The key doesn't work either now and I was careful to put the link bar (dogbone) back correctly.
I must have disturbed something? or messed up something? has anyone got ideas what's wrong please?
Baz

Update; I've got it all working now. I disconnected the battery for 30 mins to reset everything and adjusted the rod position within the white clip. It was too high which was stopping the lock closing.