Auth.net problem

Hi, I have upgraded to ecart 5 and I am using auth.net for the first time. I used the checkout wizard to build checkout pages. It seems that all of the code for sending emails, placing orders in orders tables was all out of place. But after some time I finally got all of that working now. My problem now is that using the api interface I cannot get a transaction to complete. Can you provide me with the code to place on the checkout_failure page to see what the issue is?

I tried in test mode and live mode and cannot get the transaction to authorize.net. This is the error message that I get on the checkout_failed page.
something went wrong at line 11 of your script /var/www/vhosts/cexray.org/httpdocs/checkout_failure.php.
The system says that the error code was 8, and the reason for the error was:
Undefined variable: undefVar.
something went wrong at line 4 of your script /var/www/vhosts/cexray.org/httpdocs/WA_eCart/eCart1_PHP.php.
The system says that the error code was 2, and the reason for the error was:
Missing argument 12 for ecart1_definition().
something went wrong at line 465 of your script /var/www/vhosts/cexray.org/httpdocs/WA_eCart/WA_eCart_Definition_PHP.php.
The system says that the error code was 2, and the reason for the error was: session_start(): Cannot send session cache limiter -
headers already sent (output started at /var/www/vhosts/this site.org/httpdocs/checkout_failure.php:7).

It seems that there might be a problem either on the checkout failure page or on one of the pages before this page. If you can please post back with your checkout failure and WA_eCart > eCart1_PHP.php pages. I will take a look to see if I can spot a problem with them that would be causing this error.

Hi Eric,
Thanks for your help. I finally discovered how to add the local response to the checkout_failure page so below lists the error as I see it.
Please help me understand what line item 1 is as i don't see where to fix it.

::Line item 1 is invalid

I have seen this error before, when I have seen this error in the past with others it was due to a bad value within the item. A common culprit is the size of the item's name, it can only be 31 characters in length. There are many more specific limitations that in place for the line items, they are listed here in the developer guide for Authorize.NET AIM:

AIM_guide.pdf

The line item requirements start on page 20 in this pdf doc. Take a look at these and check your items to ensure that they meet the requirements.