I already found out how to sucessfully invoke a operation in a WCF service developed with .NET (see
One question remaining is why ReceiveReply ignores the reply action header, at least in my case. My webservice is very simple:
[ServiceContract(Namespace = "http://www.juergen-bayer.net/samples/wcf")]
public interface IDemoService
long Add(int value1, int value2);
In the web.config of the service application I enabled wsHttpBinding (basicHttpBinding does not send the reply Action header back to the client, at least in my case).