I am attempting to set up authorize.net as a payment gateway for the first time, integrating with webassist ecart 6.

I created a sandbox account and have added my api login id and transaction key,

I received an email form authorize.net saying my sandbox account was active.

Whenever I attempt to make a payment, using one of the test card accounts, the transaction fails.

The only message I get is "The merchant login ID or password is invalid or the account is inactive."

I have checked my settings, but the account seems to be active, and my api key and transaction key have been corredtly entered

I have toggled my account between test mode and live mode, still no joy, (it should be in test mode right) ?