Can anyone help central locking issue?

I have an astra h 2005 with a central locking issue. It works fine when the car is switched off.as soon as I switch the engine on and off the central locking no longer works. I have to disconnect the battery and reconnect it to lock the doors via central locking. Then once engine is switched on the problem repeats. The locking works from inside the car with the door lock button. I have checked all wires etc
Has anyone had this issue or resolved it?
Thanks

Kirsty
October 2017