BMW Factory remote (one button)

Hi, I noticed discussion about the Alpine remote, but mine is the "one button type", factory fitted by BMW.

The Alarm works fine, but I cannot get the remote central locking to work from the remote.

I tested the actuators from inside the car, i.e. by pressing down on the passengers door pin, the central locking activated closing all the doors, this (I hope) proves that the electrical signal on the doors works as the drivers door locked.

Any where else I can test if the remote central locking is working ? before I end up replacing the whole Alpine alarm unit. I.e. can I test from grounding one of the pins from the Harness connector linked to the alarm box, one of the pins which is linked to the closing/opening of the doors, if I ground one of these the doors should lock Yes ?

Otherwise has anyone had an issue with the one button remote alarm ?

Cheers, from Ireland.