I'm having the exact same problem, I get a checkout failure but it actually goes through.
Did you find out how to fix that?
Thanks for your reply...after I posted, I used the Full Response and Full Request, which did have info. I also found out that the transactions are actually going through successfully to Authorize.net--so now I need to find out why I'm getting the checkout failure page.
Also, I have configured shipping via the Checkout Wizard, but there are no fields in the checkout process that show shipping quotes...do those need to be added manually? For reference, we are using UPS for domestic and USPS for international.
Thanks for your contributions to this forum--I have applied several solutions/fixes while developing this website.