I have Products and Subscriptions set up on my Forms. When a user purchases a product, then (1) the Gravity Form says it worked, and (2) it is approved by Authorize.Net. But when a user purchases a subscription, then (1) the Gravity Form says that the credit card could not be processed, but (2) it is approved by Authorize.Net.
This is similar to the topic http://www.gravityhelp.com/forums/topic/authorizenet-add-on-beta-there-was-an-error-processing-your-credit-card-1, but the tips there did not work for me -- all of the forms are entering in the correct data, as far as I can tell. I have also checked with my account at Authorize.Net, and there are no "required" fields that are not showing up in the GF list.
My webpage with the forms is http://nationalwillrepository.com/annual-account-services-fee/. Note that this form is LIVE.