Accessing a MovieClip inside of a Sprite?

I have a game where the user can drag objects around. However, these objects need to be clamped to certain areas, and are unable to move past other moveable objects.

To achieve this clamping, I have placed a 25x25 pixel movieclip inside my sprite. In my actionscript, I am then attempting to call this movieclip so I can see if it is in the way of anything. However, despite my best efforts, I have been unable to get ActionScript to even see that this collision MovieClip exists.

I’m using the following code currently to check for the existence of the clip:

trace(MovieClip(player.parent).playerCollision);

This, however, always returns ‘null’. I’m at a bit of a loss… any help would be great!

Thanks,
-BZ