Errors can be caused by the below reasons:
Maximum spend: Your mobile network may have placed a weekly or monthly spend limit on your phone bill for premium services; you can contact them to get this removed or have the limit increased.
Insufficient funds: If you are a Pay As You Go customer, you may need to top up your credit in order to use the service.
Barred: You may have a premium rate bar on your phone; you need to contact your mobile network in order to get this removed.
Mobile Network: Your mobile network may not support this payment method.