Hi,
Okay, I see.
You are using the Joomla login module and not the HikaShop one.
So it means that the transfert of the cart by the HikaShop system plugin is not performed correctly.
I'll work on that during the week end ; I should be able to provide a patch for Monday.
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.