Remove mouse-detection from a MC

I have movieclip working as button.
On mouserollover it scales up a square MC. The problem is that this square will cover other buttons when completely scaled up, and the buttons below that won’t “work”

See phenomena on
When going with mouse from button 1 to 3 it works ok, but from 3 to 1 one then the “top-stacked” button will prevent lower buttons from working properly.

I’ve put the .fla + .as to check on
As you can see I tried
sq.mouseEnabled = false;
sq.mouseChildren = false;
but that doesn’t help

Anybody any idea?