My payment for 2Checkout is being rejected

My payment to 2Checkout is not being accepted. What is the cause?

The main reasons for payment not being accepted are:

1. Insufficient funds in the account
2. Missing postal code on the client address (which you can update with your billing details)
3. Some international transactions are blocked by the bank and you will need to contact your bank to rectify this.
4. A communication failure between the bank and 2Checkout