If the transaction does not go through, we will specify the reason for the failure in our request response. We use the following transaction status codes:
OK: The transaction amount was approved.
NOK: The acquirer did not approve the transaction. The customer must contact the issuer to check if there is any issue with the credit card.
RETRY: Something went wrong with the process. You can retry with the same data. We recommend you to try 3 more times on different periods of time (first try, then second try after 2 hours after the first, etc).
You can see more of these status HERE