Most credit card failures to process are a result of a fraud hold by the bank or credit card company. These result mostly from multiple purchases made during a relatively short period of time, purchases made out of state, and large purchases made online. These can be summarized as any purchases the bank sees as being "uncharacteristic". To resolve this problem, you must contact your credit card issuer.
The second most common cause of failed credit card transactions is incorrect information. When a credit card fails to process, always verify the card number, expiration date, and CVV code. Some helpful tips: Visa, MasterCard, and Discover cards have 16 digits in the card number and a 3 digit CVV code on the back of the card. American Express card numbers are 15 digits long and have a 4 digit CVV code on the front and 3 digit code on the reverse of the card. Always make sure that the card you are using has either 15 or 16 digits in the number.
Third, some cards fail to process because there are insufficient funds available on the card. Always make sure that you have more than enough funds available to process your order prior to placing it.