Checkout does not re-direct to payment gateway

-- url of the page with the problem -- : www.liberatenutrition.com
-- HikaShop version -- : 2.2.1 Business
-- Joomla version -- : 2.5.14
-- PHP version -- : 5.4
-- Browser(s) name and version -- : All
-- Error-message(debug-mod must be tuned on) -- : ????

Hi there, please can you help.
We have used HikaShop before with no problems.
BUT
On our website www.liberatenutrition.com if you go through the checkout process, when you get to the final step and you go to the 'Redirect' screen' before going to pay on Sage Pay, the basket gets emptied and customer cannot pay for the product.

Please can you advise urgent, this is a live site.

Thanks,
Sean R.