Hmmm. You are using the latest ecommerce from Jedatech?
I get a similar error when I undo his changes in the OrderForm class. Around line 200 in the processOrder function should read:
// Save payment data from form and process payment $form->saveInto($payment); $payment->OrderID = $order->ID; $payment->Amount->Amount = $order->Total(); $payment->Amount->Currency = Order::Currency(); $payment->write();
This handles the changes made in the Payment module to implement the Money class.
Hope this is of some help. Otherwise, do you have a stack trace?