The issue is probably in the server validation on the confirm_cart.php page... If you send me a copy of that page I can show you where to update it.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.