Is this box the reason for my faulty interior light?

Hello.

I have bought a Skoda Superb, but non eof the interior lights seems to work I've check the fuse, and the fuse is ok. None interior lights work, not on the door, not in the trunk +++

I've discovered water under the carpets, and it's seems like this is a commond problem.

http://home.no/laminatkabinett/20092007.jpg

The box on the picture, is that the box for the interior light? And is the box the reason for no lights? Alarms, electircal windows, heater etc seems to work, maybe not the heater in the rear seat. (Can the box have anything to do with no heat in the rear seat?)

Last question, is there another box I've to check? On this forum, many mention a "node"? Where is the "node"?