Fast checkout OK, normal route - error

#1

I get this error when using the Virtuemart checkout process and selecting Google checkout as an option:

Oops!
Red Flag Technologies Ltd has sent Google a shopping cart with errors in it. We'll contact them to ask that they fix this problem. As this could be a temporary issue, you can go back in your browser to try checking out again.

Fast checkout works fine. Can you advise a fix?

regards

Peter

#2

I should add that the integration console gives this message:

17 Aug 2008 11:12:37 GMT+01:00 Error - Carts must contain at least one item.

#3

Do you get this error for every item? Try signing up for a sandbox account at http://sandbox.google.com/checkout

The sandbox account gives you better error reporting.