Credit cards can be declined for a number of reasons. Roost generally isn't notified of the specific reason.
Please check that you're entering your credit card number correctly, that your card has available funds, and that your card hasn't expired.
If you're getting an error when you try to pay, we recommend reaching out to your bank or credit card company for more information. Inform them of the amount and when tried to make the charge so they can let the transaction go through.
If your bank or card issuer isn't able to help, you may want to try another payment method.