add to cart button doesn't work

-- url of the page with the problem -- : elportalnaturista.com
-- HikaShop version -- : 2.3.1
-- Joomla version -- : 2.5
-- PHP version -- : x.x.x
-- Browser(s) name and version -- : google chrome 35.0.1916.153 m
-- Error-message(debug-mod must be tuned on) -- : Error_message

nothing happens when i click add to chart button

Hi there
Sorry, I disabled 'Use AJAX when possible
for add to cart buttons' - and that seemed to fix the issue. Thanks for your help.