AS2 Connection - MDN received by PArtner is empty

We have webMethods 9.12 , we receive EDI files via AS2 from external org. They expect Sync MDN. WebMethod logs shows MDN sent with payload. But partner side they see error as

MDN parsing error: java.lang.Exception: MDN received with no Disposition header.

Is there any configuration i should do on for this?

Hi Jackson

please check for Fixes for TN, EDI and whatever you have installed to get these packages running.

Might be that there were an regarding Disposition Header which has been fixed meanwhile.