Whenever you see Security Code Error on the page after you enter all your credit card information, please make sure that you enter the correct CVV or verification code for your card. The verification code (or CVV) is a physical signature for the actual credit card you are holding and it will change when you receive a new card (with a new expiration date, etc.).
If you are quite sure that you put everything correctly then this is probably because of your credit card company or bank declines this transaction for security reason. Under this circumstance, please contact your credit card company or bank to unblock the transaction.