Serials are not being automatically assigned

I'm trying to get this working, but it doesn't seem to be.

This is what I've done so far:

- I've created a coupon generator in the plugins
- I've created a pack and assigned the coupon generator
- I've generated 5 serials
- I've created a product in hikashop and I've assigned the pack to the product

The problem is - when I buy the product, a serial number IS NOT assigned to the purchase. There are still 5 serials left, and all of them are free, even after paying in paypal and receiving the confirmed payment email.

It's OK - I hadn't configured hikaserial properly. I needed to write confirmed in the box!