Error when entering contact details

-- url of the page with the problem -- : hartsco.com/index.php/shop/category/13-sonos
-- HikaShop version -- : 2.2.1
-- Joomla version -- : 3.1.1
-- PHP version -- : 5.3.15
-- Browser(s) name and version -- : Chrome 29.0.1547.76 m
-- Error-message(debug-mod must be tuned on) -- : Error_message

PHP Warning: in_array() expects parameter 2 to be array, null given in C:\Inetpub\vhosts\hartsco.com\httpdocs\components\com_hikashop\controllers\checkout.php on line 770

Add an item to the cart then proceed to checkout. Enter contact details then press next.

Thanks Nicolas - working now