Google CHeckout installed and working - then turned grey

Hello, First time using this forum. I am website developer/hosting comapny working on a project for a client (using zencart for the first time). I successfully installed google checkout a couple months ago. CLient then switched to "free shipping" with orders over $5 and now google checkout option greyed out and gives the following error. Not sure where to go to fix the problem.

ERROR
Not available for these items
What is Google Checkout?
* There are multiple shipping options selected and they use different shipping tax tables or some dont use tax tables

Would appreciate any help here.