...actually...its all good...i found the problem :) I hadnt edited this line of code:
if (is_numeric($ATC_itemQuantity) && $ATC_itemQuantity != 0) {
$DinkyCart->AddToCart($ATC_AddIfIn, $ATC_RedirectIfIn, $ATC_itemID, $ATC_itemName, $ATC_itemDescription, $ATC_itemThumbnail, $ATC_itemWeight, $ATC_itemQuantity, $ATC_itemPrice, $ATC_itemOptions, $ATC_itemOptionsPrice, $ATC_itemShippingCost);
I forgot to put the new field reference at the end :)
Chris