error on check out

-- url of the page with the problem -- : www.webmasta.my/shop
-- HikaShop version -- : 3.0.1
-- Joomla version -- : 3.6.5
-- PHP version -- : 5.4.45
-- Browser(s) name and version -- : chrome
-- Error-message(debug-mod must be tuned on) -- : Fatal error: Call to a member function enqueueMessage() on a non-object in /public_html/components/com_hikashop/controllers/checkout.php on line 546

hai, my client keep complain that they cannot make payment as they get this error. please help

Fatal error: Call to a member function enqueueMessage() on a non-object in /public_html/components/com_hikashop/controllers/checkout.php on line 546

please help