Hi,
There is a little mistake in the "unassign" function. It would be fix in the next release.
I am currently working on the version 1.4.0 with serial history so if I can't release the new version during the week end, I would patch the current package with the fix.
If you're really hurry, I can send you the affected file by email.
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.