My first call to auth.net (handled by some jerk who didn't know what the hell they were talking about) said that the error message simply meant the transaction went through fine but my account was still set to test mode. This was obviously not the problem, and changing to live mode did nothing but remove the "(TESTING)" prefix from the error message.
On my second call, however, they said that I was actually suppose to be using the API login code that was issued with the transaction key which, as far as I can figure, is exactly what the ecart checkout wizard said NOT to use.
After replacing my web login with the API login key, the checkout process appears to be working super-de-duper-ly.
The verbiage should probably be changed in the next ecart update to reflect this. If it already says that (and my dumbass just misread it), then perhaps a slight update to just clarify a bit more that the API login is what is required, and not the web login.
