Checkout failing to move forward

-- url of the page with the problem -- : hopgarland.com
-- HikaShop version -- : 2.6.3
-- Joomla version -- : 3.5.1
-- PHP version -- : 5.6.14
-- Browser(s) name and version -- : Safari 9.1
-- Error-message(debug-mod must be tuned on) -- : No error message

The checkout process for this page is simple, Everything is done on one page, no login or registration required. This site has been working fine but when I updated Joomla to 3.5.1 the checkout stalls. No errors, no messages, just the current screen refreshes. I think it's something to do with the login step as I have moved each of the steps to a page of it's own and when the login step is on the first page I can't get the process to move forward. I've updated HikaShop to 2.6.3 and the checkout still stalls. Any ideas would be appreciated.
regards
roman

On seeing your response and seeing the transaction you initiated I wondered if I had been working with a cached version of the old site. I just cleared all caches and cookie data and tried again and still can't get the shopping cart to leave step 1 and forward me to PayPal. I have also tried several browsers - Safari, Google Chrome and Firefox, all with the same result. When you click the "Register" button it just refreshes the checkout screen. I am at a loss as to how to proceed?
regards
roman

Thank you for your help. I just tried a different email address and it worked fine.
regards
roman