The most common cause for a payment to fail is when an official's bank account information changes, and the official does not update their banking information in assignr.com. When this happens, the payor and the official will receive an email notification.
The official will need to update their bank account information.
assignr.com will automatically update the statements that could not be paid, marking each one as "unpaid". When you process payments again, the unpaid statement should show up as one that needs to be paid.