The Data Validation Tool helps developers check the syntax of name/value pairs. This tool has moved to http://developer.authorize.net/bin/developer/paramdump. Please update your integration to point to this new URL so that you can verify that all field names and values in your transaction request are correct.
Changing the Transaction POST URL in your script from https://test.authorize.net/gateway/transact.dll to http://developer.authorize.net/bin/developer/paramdump will display the transaction results. You can then verify that all field names and values in your transaction request are correct.
Please Note: