Effective November 20th, 2013, Google Checkout was shut down and is no longer processing payments.
Google Checkout To Shut Down On November 20: http://www.webpronews.com/google-checkout-to-shut-down-on-november-20-2013-10
To those users who are using Google Checkout on their website, kindly check the link below.
Retiring Google Checkout Announcement: support.google.com/checkout/sell/answer/3080449?hl=en
With Google Checkout stopping its service, we will stop supporting Google Checkout on our next major release.