XI3.0: Soap Sender with HTTPS

I have enabled HTTPS on our J2EE stack.

We have a soap sender which works fine using http and username/password authentication.

When I switch "HTTP Security level" on the SOAP sender to "HTTPS without client authentication" and sends the SOAP request to the HTTPS port XI (j2ee) returns a HTTP errorcode 403 Forbidden. No explanation, and I can't find any traces in the logs.

Please help/advise!

-AD