Need a little help with queryDefMethodsSoapClient - using the SOAP client

Through the forum, I've been able to formulate working ExecuteQuery examples in SOAP U/I.  However, when trying to get the same to work in c#, it isn't clear to me how to get the response data.

Here's a snippet of my code:

XmlElement response = null;
            try
            {
                XmlElement xml = buildQuery();
                response = client.ExecuteQuery(secureToken, xml);
                client.Close();
            } catch (FaultException f) {

The ExecuteQuery runs without exception, but when I look at the returned XmlElement, it only contains the empty structure of a response without any data in it.

For example, <service-collection xmlns=\"urn:xtk:queryDef\"><service /><service /><service />....

Where's the data?  Could someone share a working code snippet of getting the returned data -  in any language.

Thanks