The LobSystem (External System) returned an object of Type '{0}'. The metadata for this Parameter indicates that the External ...

The LobSystem (External System) returned an object of Type '{0}'. The metadata for this Parameter indicates that the External System is required to return a Collection (something that implements IEnumerable or IEnumerator). Business Data Connectivity cannot use/convert a '{0}' to an IEnumerator or IEnumerable.