Rear reading light problem

Good morning all

One of my rear interior lights is not responding to the either the central locking being activated or the doors being opened/closed, all the others work fine. It still works when being used manually so it obviously has power to it and if set permanently to the 'on' position will turn on/off with the central locking but this obviously means that it would be on whilst driving. The door on it's side registers as being open on the display so I'm not sure what the problem could be?

I am having the control unit in the drivers door replaced at the beginning of next month as there have been a few occasions of the drivers door not unlocking with the central locking, is this likely to be effecting a single light at the same time?

There are plenty of examples online of different/all interior lights failing but none appear to be exactly the same situation as mine so any ideas would be welcome. 

Regards

Ross