AS2 MDN Error "processed/error: authentication-failed"

I am getting the following error related to a MDN in WM 7.1:

Disposition: automatic-action/MDN-sent-automatically; processed/error: authentication-failed

Are you sender of MDN or receiver?
If you are receiver of MDN,Check the Activity logs for both EDIINT and MDN Transaction in TN…

I am the receiver. Thanks I will look in the logs.