Are you getting an error for insufficient funds or that your card was declined. This could mean exactly what it says, or it could mean your bank is blocking this transaction.

1) Verify that you entered the correct card information, including zip code. If that doesn't work, call your credit card or bank and ask them why it's failing.

2) Try a different credit card.

3) If you don't have another card and find there is no block on your card from your bank, please submit a support request with a screenshot of the error you're seeing.