OK, 1/2 my bad ;) i just noticed the problem appears only on one addon livery, the conviasa one. It works with all the others so I think there are some texture links missing for that one.

Dome light is still not working but I can install one myself in the aircraft.cfg


EDIT: fix for missing textures on addon liveries, interior or exterior:

Inside the texture.cfg of the livery, check wether there are valid source directories in the "fallback"-entries. In my particular case there was an "LM" given by the creator of the livery, where the real folder was called "night".
It also happens when there is the wrong plane model "737-100" entered.
This is due to captain sim's changes in file structures and their decision to release the -200 as base pack. Gives you some headache when installing liveries that were created during public beta testing.