If your most recent transaction was declined, you would have received a notification with the reason for the decline.
If it was because your daily or monthly spend limit was reached, you can increase the limit and retry the transaction.
If it was because a channel was not enabled, you can turn on the toggle for the specific channel and try again.
If it was declined because a specific country was not enabled, you can select the country under the “Select Countries” option and try the transaction again.