Hi,
Would it be possible to have more details about your actual "attach serial" configuration ?
Having also details about the product and the pack can be also useful (if you are using variants, if you're using an item custom field to specify the product price, etc).
Thanks
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.