Forgive me also if the answer to my question lies deep inside the hundreds of thousands of pages below. I have been searching all over the net for days, trying everything but I'm hitting a brick wall .
OK, here is the problem: The "Place your order now - .." button in Google Checkout is grayed out.
A few days ago I was able to do a complete checkout for a digital product in the sandbox environment. I was able to set order status from Zen Cart Admin UI, or from Google Checkout Seller UI and all of this over SSL while everything kept perfectly in sync.
When I set the store to start using the production system the "Place your order now -..." button started to be grayed out. Setting the exact system back to sandbox made no difference what so ever -- the button in Google Checkout stays disabled (grayed out).
There are no messages in the response_messages.log and response_error.log (except the ones when the sandbox worked), nor anything inside the Google Checkout Sandbox UI.
I have tried many variations on shipping options, tax zones, table rates, free shipping, carrier calculated and on and on to no avail.
Please also see my Issue on the code.google.com system:
http://code.google.com/p/google-checkout-zencart/issues/detail?id=24
There you will also find a sample of the cart XML.
Any help would be greatly, greatly appreciated.
Problem site: http://www.justvocabulary.com/store/