AS2 Receiver channel in Error

HI Experts,

Am working on a scenario - ECC -> SAP PI (7.4 with B2B Addon SP01) -> External Partner.

Using the AS2 receiver adapter to send data to the external partner. I have configured all the necessary parameters like

certificates import in NWA and configuring the details in channels accordingly. When I trigger any idoc from ECC, I see the

below error message in PI for the AS2 receiver channel -

MP: exception caught with cause javax.resource.ResourceException: Message cannot be delivered: java.io.IOException: Cannot write this object. It has to be an instance of iaik.security.smime.JMailSMimeSigned or iaik.security.smime.SignedContent!