1) Try changing focus to another field before clicking OK... or even click on the help button first.
2) Try "subtotal of column value" and use the quantity column
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.