MDN Disposition-modifier-extension is error: insufficient-message-security

Hi Experts

I am using scenario IDOC--PI--AS2.

I am getting below error in Comm Channel.

but it is successful in Message monitoring we are able to see this error in Audit log.

Information: Requested MDN Properties :
MDN Type : Sync ; Signed MDN : No; MIC Requested : No;

Information: received MDN (795 Bytes)

Information: received MDN (795 Bytes)

Information: MIC (0UG1zY0UcXj9YSal+S/UvBIClM4=) is calculated using SHA1
algorithm.

Information: CONTENT-TYPE of MDN is : multipart/report;

Information: MDN is NOT signed

Error: MDN with action-mode automatic-action, sending-mode
MDN-sent-automatically and disposition-type processed received

Error: MDN Disposition-modifier-extension is error:
insufficient-message-security

could you please suggest

Thanks

Prem