This is because the three digit CVV number you have entered has not been able to match it to the details held at you bank.
The three digit security code is known as the CVV (Card Verification Value) or CVN (Card Verification Number). It is a number that is printed, not imprinted, on your Visa, Mastercard or Bankcard.
Visa, Mastercard, and Bankcard card members can find their CVV/CVN number in the signature area of your card. Your card number should be printed here along with a three-digit number at the end. This is your CVV/CVN number.
If you have seen this error the transaction will have been voided by the payment system, but you may still see them on your bank account. Occasionally the bank you have used to make the payment do not act on the void notification straight away. But you can be assured that the funds haven’t been taken out of your account, but will be on hold until your bank has acted on the void request. If you call up your bank they should be able to see the void request and remove the fund holding.