The tracking code in your page looks correct, but you are missing the View Cart code that would display the cart as an overlay "inside" your own page, and that is required to use our version of the GA tracking code. Just make sure you paste at least one complete block of your View Cart code from Seller Admin into every page that has any number of Add to Cart buttons. Also, make sure your browser settings do not block "third party" cookies if you will be placing test orders yourself.