Check to make sure you have POST set as the method in the HTTP Remote Call section:
Click the Cart Setup tab
Advanced Settings
Remote Call (IPN). Then in the drop down box select POST.
Click "Update Record" and save your changes.
Also, if you're seeing this and use Paypal as your payment method you might need to check the Paypal setting in Mals, and choose the first (just the words...)
PRODUCT DESCRIPTION
The cart transfers the customer over to PayPal to pay for the entire cart contents as a single item. You can choose the way the description is set:
Just the words: Order number: XXXX
Try to push all the products into the description. It will be cut off at 127 chars.
