Making a Select Box

I am trying to make a select box for an RTS Flash game. For the most part I have it working, I can click and drag a box from top left to bottom right, however it doesn’t work when I click and drag from bottom right to top left. Swf can be seen here and code can be seen here [URL=“http://ec2-72-44-50-95.z-1.compute-1.amazonaws.com/example/SelectBox.as”]here any ideas on what code I can add to make this select box work properly?