Problem adding compression to message sync

I am having a problem gettng a compression sync to work. To troubleshoot the problem, I created a "null" sync that does nothing but push the messages through. This "null" sync exhibits the same problem as my CompressionSync. With this "null" sync, it works, returning a dataset but the following ProcessMessage on the server side always has null responseStream and responseHeaders after calling _nextSink.ProcessMessage (synchronous call). This is a problem since as I understand it and every example that I have found, shows that I'm supposed to compress that stream. I've tried both soap and binary formatting. When are the responseStream and responseHeaders supposed to get created and who (what code) is responsible for it (responseMsg is not null)

Any help would be greatly appreciated.

Thanks

public ServerProcessing ProcessMessage(IServerChannelSinkStack sinkStack,

IMessage requestMsg,

ITransportHeaders requestHeaders,

Stream requestStream,

out IMessage responseMsg,

out ITransportHeaders responseHeaders,

out Stream responseStream) {

sinkStack.Push(this, null);

ServerProcessing srvProc = _nextSink.ProcessMessage(sinkStack,

out responseMsg,

out responseHeaders,

out responseStream);

return srvProc;