I have a payment form that users the AIM method to post to Auth.net via PHP. It works great right up to the moment that Transaction key don't work. I have get error message ---- AuthorizeNet Error: Response Code: 3 Response Subcode: 1 Response Reason Code: 103 Response Reason Text: This transaction cannot be accepted. I get the reason from guides API. The transaction key is invalid. I set up the new transaction key and make it work. I want to know why transaction key is invalid. Thanks.
