User blog:Bowser32/I have a problem I can't figure out

I have multiple npc houses a few of which have npc's in them but the others aren't valid housing, yet every room is exactly the same and its weird because earlyer in my game I actually had npcs living in those houses. Each house is 10X6 with two wooden doors on each side, a chair and a table. They're also made with wooden walls, floor and ceiling and wood wall.

Please help