First, we are so sorry! There are a few reasons this could occur:
Bank declines the charge
Card has insufficient funds (this error will also sometimes appear on prepaid cards, even if the funds are there)
Card is expired
Something on our end :(
If you are having problems submitting the form on the Subscription Update page (where you select the campaign subscription), try adding your card first on your Billing Info page. You can access this in the left nav from your account settings or any campaign subscription update page.
Sometimes by adding the card first, the charge will go through without an issue. If not, you will at least get an error message on why the card is not being applied.
Please reach out to us at email@example.com if you need any assistance or feel these errors are incorrect. We will try to assist in getting your subscription set up. We also offer a Paypal Subscription option! :)