@NightRaven4562 It's a little hard to tell from that pic which room is staying dark. If the house is in a dark world and you do not have regular or complete walls and a roof, then I don't think lights will make it as bright as normal rooms.
What is the Gallery name of the house? Maybe someone here can download it and do more testing & make better recommendations on how to fix this.
I don't know if I ran into the same problem but I had one that's like this. I was modifying a house over in the city that came with City Living (San Myshuo-something) I put in stairs for a third story then the second story lights go to off, used the Undo command and the lights came back, I put in a latter and it goes dark again, undo has the same effect. So I'm stuck at 2 stories right now.
Possibly I am putting too much stress on that specific room's lighting controller(in the program itself) and it's crashing(buffer overrun?) so to keep the game from locking up completely the program ignores the lighting for that room and just gives it an off state. I am just guessing, the problem popped up just before I was about to quit for the night so I haven't had a lot of chances to experiment with it.
You said you did the walls again but did you draw them or use the box tool? If not then try using the box tool instead.
