Please be advised that the transaction may be not successful due to some of reasons:
In correct card information (Card number, Card holder name, Date of expiration...).
Not enough credit balance (daily or monthly) or Insufficient Funds. You should check your bank account balance.
Your card has not been activated for online payment. You should contact the Issuer Bank for the card activation.
Your bank has not been approved for online payment. You should contact the Issuer Bank for the card activation.
In this case, you should solve the problem then you can make payment again to secure your reservation.