Hi,
You should check your PHP error log in order to see if you got a PHP fatal error.
Setting the "error report level" to "maximum" in the Joomla global configuration might also help you to display the error in the page directly.
You might also see to update HikaShop to a more recent version, the 2.2.1 has been release more than one year and an half.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.