Interior light fault on Vectra c desighn?

I have a 2006 Vectra c design and the interior lights (front and back) have stopped coming on when the car is unlocked via the central locking. They will not switch on manually but all other lights work OK. The switches on the interior light are illuminated OK. The reading lights do not work either. I have checked fuse 12 and it is OK. I had a similar problem on a 2002 Vectra and I never did fix it. Anyone know of this problem?