AS2 Certificate based authentication issue for Receiver Channel

Need help in solving issue with AS2 Receiver channel not passing certificate for authentication. The following configuration is in place:

1. Signed certificate(private key) has been installed in the NWA keystore.
2. The corresponding RootCA certificate related to item 1 has been installed in Trusted CA's NWA keystore.
3. The target URL SSL certificate has been installed in the NWA keystore.
4. The target server has the client certificate (public key) installed in their keystore.
5. The target server has the public key Trusted CA installed in their keystore.

When calling the URL with the above configuration, the SSL negotiation is happening but client certificate is not being passed for authentication from SAP PO to target server.

In order to test the certificate validity, we have used the certificate on a HTTPS connectivity with the target server and this has worked - SAP PO is passing across the required certificate for authentication.

It seems there is an issue with the AS2 adapter. We are on the latest service pack for the AS2 adapter (Service Pack 04).

Suggestions on resolving the above would be much appreciated.

Thanks

Shalendra