bug detected

Hello,
I’ve disable billing and also shipping addresses from the checkout as I don’t need them, but during the checkout, after clicking on “Next Step”, the next error messages are shown, as if the billing and shipping form where there (they are not as I disabled them):

Shipping Address: Please enter First Name
Shipping Address: Please enter Last Name
Billing Address: Please enter First Name
Billing Address: Please enter Last Name

http://wordpress.org/extend/plugins/ready-ecommerce/