function CalculateOrder(form)
{
if (form.item_name.value == "Butterflyking Video (DVD)"){
form.amount.value = 14.00;
   }
else if (form.item_name.value == "Butterflyking Video (VHS)"){
form.amount.value = 10.00 ;
}
 else{
form.amount.value = "errors" ;
   }
}
  
function isValid() {
  if (document.form1.amount.value != "errors")
  {
 return true;
 }
 else
 document.getElementById('error').innerHTML = '*Please select a video format';
 document.getElementById('item_name').className="storeerror";
 return false;
}