I am attempting to set up a sandbox account in our ERP system and auth.net just told me they have no idea why it won't work. We had a live auth.net account set up and it worked fine. We are 3 weeks from going live and I really do not want our staff "testing" with our live accounts. for merchant name they told me to use the api login and I also tried api login/sandbox user name. I have tried transaction key and transaction key/sandbox user password with no luck. Any help would be greatly appreciated.