We are integrating with eCheck and the Reporting services using C# .NET AuthorizeNet NuGet package.

ECheck is authenticating fine, calls to the Reporting service are failing with the E00007 error.

I am using the ApiKey and TransactionKey specified in a constant for both calls, so I know the same values are being used in both.

Examining both calls using Fiddler2 I have confirmed the following:

The eCheck call is being sent to https://secure.authorize.net/gateway/transact.dll.

The Reporting call is being sent to https://api.authorize.net/xml/v1/request.api 

I have confirmed that the ApiKey/TransactionKey values are passed correctly into the <merchantAuthentication><name>]</name><transactionKey></transactionKey></merchantAuthentication> elements.

 This is a production account.

Any ideas on where I can look next to resolve this?