loadMovie and masks

I’ve found this huge problem, and I’m wondering if any of you have ever had to tackle this one before:

I have this MC that loads in a .swf when a button is clicked, and this box that moves down to make space for the swf. This box is designed so that it moves to 10 pixels below the loaded movie, regardless of the size of the movie.

The code for that box is:
onClipEvent (enterFrame) {
this._x = (_parent.canvas._x-_parent.canvas._width/2);
this._y = (_parent.canvas._y+_parent.canvas._height/2)+10;
}

The .swf has this rather large movieclip that is masked.

Here’s the problem: When I load the .swf, I see the stuff that is masked, and nothing else, but the box moves way down, as to suggest the masked contents are still there, and using up space, only not visible.

I know the box works because if I load in a JPEG, the box moves down accordingly.

I’ve tried putting the MC and it’s mask in another movieClip, but no help. I’ve tried using the attachMovie, and having it load in at the 3rd frame, and still nothing.

I cannot have anything set, as the loader MC is also loading other material, so I can only make changes to the .swf.

Help!

Thank you

–iMat