Hello,
If you want to attach a PDF depending a serial, you can use the "pdf serial" plugin and not "print" the serial on that PDF.
That plugin is working like the "attach serial" one but is using PDF instead of images :
www.hikashop.com/support/documentation/1...ns-attachserial.html
Otherwise, if it would be related to a product, HikaShop would be the component to target and I would suggest you to open a new thread in the HIkaShop section of the forum for that.
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.