Make sure the person has a valid EFT or card authorization. This will be found on the person's profile in Back Office under the "Economy" tab. Note! If the subscription is paid by someone else, the EFT or card authorization should be added to the payer's profile.
Check the “Deviations” tab on the subscription to see if it has been frozen or given a free period.
Check the “History” tab on the subscription to see if there has been any other changes to the subscription that could be the reason for the issue. If money could not be drawn due to lack of funds (the customer didn't have enough money on the account), you will see that here as well.