Audi A5 Sportback rear door not locking

[carbob]

My 2014 A5 Sportback doesn't lock on rear driver's side door.
Not with the key fob or with the manual lock.
The electric window works and the fuse is good.

I presume its the lock actuator?
I have got a replacement, but before I take the door apart to replace, have I missed something else to check?
If its not the actuator what else might it be?

Thanks