I have a live account that I tested myself with an actual credit card and the order went through and everything works just fine.  I plan on releasing our store to some internal people in our organization.  I was thinking of putting the Authorize.net account in "test" mode and then letting everyone test, but the account is used for other sites so I can't do that.

I registered as a developer and got a test account for their sandbox.  I have an API Login and Transaction Key and they sent me a list of "test" CC numbers.  However, I tried a bunch of different Payment Gateway settings but could not get the checkout to work with these settings.  Has anyone successfully tested an Authorize.net configuration into their sandbox system?  I've tried checking and unchecking the "test mode" option, as well as actual CC numbers and the test CC numbers.  No luck.  Thanks.