Thank you for shopping with us. However, the transaction has been declined.

i am using latest version of wordpress, and have installed sark migs plugin ,it appears on checkout page but does show bank needed detail is that how it works only name of service and picture of master card , second thing when i click on book button it returns to me with this message “Thank you for shopping with us. However, the transaction has been declined.” kindly Guid me how to fix this issue