error when clicking on add to cart

I am having an issue where when i click on a add to cart it freezes the browser on the circle icon that show that's its adding it to the cart and nothing happens.
Using firebug i can get these errors
: http://www.vats.ca/errorpage.htm?aspxerrorpath=/NopAjaxCartCatalog/CheckIfProductOrItsAssociatedProductsHasAttributes

ReferenceError: data is not defined
http://www.vats.ca/Plugins/SevenSpikes.Nop.Plugins.AjaxCart/Scripts/AjaxCart.min.js
Line 6.  Has anyone experienced these before?

Hi, 

It looks like the server returns an error page. Please submit a ticket, mentioning your nop version, plugin version and credentials to your site, so we can take a look at it and find the solution to this issue.