The business's credit card processor marked your transaction as fraudulent? Or your bank rejected it? Or the item was out of stock and their site handles that i

The business's credit card processor marked your transaction as fraudulent? Or your bank rejected it? Or the item was out of stock and their site handles that in an unclean way? I'm not in a position to speak confidently to why a website rejected a transaction, but if you're going to, you really ought to be able to back it up with something more than "why else would it be?".