"Try again" doesn't really tell us much about the real error you're getting. But assuming it means "server can't reach the credit card company", your best bet is probably to raise a support request at https://support.atlassian.com - they should be able to get to the errors being thrown.
I'd say that there's two possibilities - first, what you're providing does not match what the bank expects, or second (and much more likely), that your input is being damaged or lost on the way to the bank for verification. In both cases, it's definitely something support need to look into, as the errors we get as end users aren't telling us enough detail!
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