If you are talking about this mod:
Blue Interior for FM_NewInteriors v1.0
http://www.subsim.com/radioroom/down...o=file&id=1566
did you download and enable the FM_NewInteriors v1.0 mod first? The Blue Interior only adds blue lighting at night to the Type VII interiors contained in FM_NewInteriors, it does not include all the new fully modeled interiors.
For that you need FM_NewInteriors v1.0 mod enabled and working first, then add the Blue Interior mod on top of it.