It's always frustrating when your customer has trouble purchasing your photos, especially when their credit card isn't accepted at checkout. This could be for a variety of reasons - the most common of which we have listed below:
Make sure your customer has entered their CVV code correctly. It is commonly found on the back of their credit card, above the magnetic strip.
Ensure that they have entered all of their billing information correctly. Even something as simple as their ZIP code being incorrect can lead to their card being declined.
Have your customer check the expiration date on their card - if it is recently expired, that might be the cause of the issue.
Make sure the card they want to use is eligible for making purchases. Some cards might be limited in what types of purchases it can make, or might not yet be activated.