Hi,
If you have a full blank page ; please check your PHP error log because you should have a PHP fatal error.
Just like that and regarding your screenshot, I could suppose that you have an override for the notification email and that override might contains an error.
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.