swapDepth Help

what im trying to do:

attach 4 boxes to the stage (mcBox1…mcBox4)
you can click and drag the boxes and drop them over an “X”
once the box has been dropped its pushing its respective number into an array (arrayX)

once all four boxes have been placed over the “X” im comparing the arrayX string with another array (arrayY) which has the correct combination if the arrays match you win if not it clears arrayX and the boxes are randomly placed on the screen so you can try again.

well ive gotten 85% of it working but im having trouble with the swapDepth() it only works when i “double click” the box

if anyone can help or see where ive gone wrong i’d appreciate it
thanks

file can be downloaded here:
http://www.midnitefx.net/swap.fla