Central locking passenger door not opening

[Rusty789]

Can someone please help, my passenger door on my 55 plate A6 will not unlock via the remote key fob or by the unlocking button on the drivers door. The only way that the door can be unlocked is by using the lever on the inside of the passengers door. I have tried changing the setting on the MMI, but this makes no difference. The door locks fine via the key fob and automatically once you start moving.

[SuperCharger28]

Somebody may have activated a child lock?

[Rusty789]

Sorry, should have said its on the front passenger door, therefore I don't believe that it could be a child lock, but thanks for the response.