apartments from gallery

It might be that you are trying to place the room (apartment) one square off or have it rotated the wrong way. I've had the former happen a lot when I try to place my own apartments down on lots I've specially created them for. Apartments are just finicky.

Another possible reason is if the user placed the room on another lot, edited it there, and then reuploaded it, it is entirely possible that it was expanded out a row making it not fit.

Apartments are tricky. It has to specifically fit the exact place it's designed for. Best way is to knock out a few walls and make it one 'room'.

it's the Stonestreet apartments from Eco Living and it's just one perfect square. I am aligning it perfectly but won't place it. It will however allow me to place the apartment out of bounds and furniture and stuff are sticking out of the walls. It makes no sense.

Check to make sure there isn't some little bit sticking out over the line, especially if they've MOO'd it, that may be causing something to hang over the line as well.