Isolate your doors and loop. The code will work on its own without other elements. I've had this same problem before and it's usually because the invisible portion of another movieclip is overlaying the button objects.
If you're adding other MovieClips dynamically that may overlay the doors, locate the container movieclip of those objects and set its properties mouseEnabled
and mouseChildren
to false
. The container and its child objects will no longer receive mouse clicks instead of your door movieclips.
The answer here clarified the issue for me: