adding script

This was a page I did ages ago.... http://www.ecurry.net/menu2.php The problem with it is when you add or subtact an item is it always button press behind. This must be because of the way the page self submits or something? The script is here.... http://www.ecurry.net/calculate.phps This is ok when I put it in an iframe it updates on every click. http://www.ecurry.net/menu.php thanks, Ross