Check your Business Connector Configuration

Lately I had the following error in the eventlog of the SSRS Server. After several checks I found out that this missleading error message was produced by a business connector call to an AX environment that was no longer up and running.
After changing the business connector configuration everything is working fine again.

Message:

Protokollname: Application

Quelle:        Microsoft Dynamics AX Enterprise Portal

Datum:         24.12.2014 14:48:45

Ereignis-ID:   1000

Aufgabenkategorie:Keine

Ebene:         Fehler

Schlüsselwörter:Klassisch

Benutzer:      Nicht zutreffend

Computer:      abc.defg

Beschreibung:

Beim Anmelden am Server durch Benutzer abc.defg\ABCDEFG ist ein Fehler aufgetreten, als der Dynamics-Adapter LogonAs von Prozess 'ReportingServicesService' und Threadkennung '26' verwendet wurde.

The server is unavailable. Microsoft Dynamics will try to connect to other servers in your configuration.

Microsoft.Dynamics.AX.ManagedInterop.ServerUnavailableException

   bei Microsoft.Dynamics.AX.ManagedInterop.Session.LogonAs(String user, String domain, NetworkCredential bcProxyCredentials, String company, String language, String objectServer, String configuration, String tenant)

   bei Microsoft.Dynamics.Framework.BusinessConnector.Session.DynamicsAdapter.LogonAs(String user, String domain, NetworkCredential bcProxyCredentials, String company, String language, String objectServer, String configuration, String partitionKey)