I had to cancel a request after I had printed the mailing label with postage.  When I canceled, did it credit back the requestors credit.  How can I get my prepaid postage back.

wondering

yes, when you cancelled the transaction the requestor got their credit back BUT, you will not get your prepaid postage back...that is non-refundable.

For future reference - don't cancel requests once you've printed postage. You have no obligation to do that and you shouldn't be asked to once you paid for postage, its the same as if you had already mailed it. Make the requestor buddy you a credit before you cancel the transaction to reimburse you for the postage.

Depends on why the transaction was cancelled. If the requester wanted it cancelled, I could see asking them for a credit as a postage refund. If the sender cancelled (couldn't find the book or discovered it was damaged, for example), then the requester doesn't owe them anything.

You can still use the printable postage label though. Next time you have a book order, DON'T use printable postage, then just cut out the requester's address and tape it over the address on the printed postage label. Your DC will be unreliable for that particular book but you can always black that out if you want to.