Savannah is right - the room mods are done by using the game 'maps'. Look at the image files in the game and you'll see what I mean. An alteration to one affects the others.

Lewanda mentions in the posts that accompany her files whether or not you need to download one of her other mods to go with the one you're looking at. Go back and read whatever post was with the mod you're trying to use, and then download whatever other mod she mentioned. I guarantee that'll fix your problem!