使用PHP处理Authorize.net中继响应

I am kind of a newbie when it comes to online CC processing integration. I am in the Sandbox at Authorize.NET trying to configure my server to process SIM orders where the payment page form resides on the Authorize.net servers and processes the order. By default it looks like the confirmation is on their sites, and e-mails can be configured to be sent to the buyer and the seller. That is all working in the Sandbox. However, I am trying to capture some of the order and processing information on my server using the relay response. My processing page is accessible on my server, although I must say that I have .htaccess limited intermittently because it is still in development. I turn that off when I am testing.

The error that I am getting is:

An error occurred while trying to report this transaction to the merchant. An e-mail has been sent to the merchant informing them of the error. The following is the result of the attempt to charge your credit card.

  This transaction has been approved.

It is advisable for you to contact the merchant to verify that you will receive the product or service.

I can't tell if they are POSTING data to my page or not, and I'm not really clear on what goes on the response page and how to parse the response. I am using the PHP SDK provided by Authorize.NET. The rest seems to be working. I am getting e-mails for the buyer and the seller and the order is proccessed but I'm not capturing the information on our server. What I would like to do is bypass their confirmation page, receive the relay response, create a custom confirmation and capture some of the data for our database. I'll keep digging because I made a fair amount of progress just reading the docs. This one is particularly useful.

Thanks.

I figured it out. There was an error on the page giving a "500" error. I have to say, it is a little strange the way they have it set up. They are POSTING to my page, where I am capturing the POST data, writing stuff to a database, and then creating a custom confirmation message, although it must be via a header redirect because it shows up on their server (their domain is in the address bar). It all works, but apparently, any SESSION variable values are not available to my script in that case?