Can you help a .Net Newbie with what is probably a stupid question?!

I am calling a WebService and passing in an XML string, my understanding of the WebService is that I pass in the XML and it updates it with a result.

I have manged to work out the authentication, and I get no error, but the XML I send in is not updated. I wonderred if I need somehow to implicitly say I am passing my parameter by reference instead of by value?

WebServiceLink.HTNGHeaderValue.From.Credential.userName = UserName
WebServiceLink.HTNGHeaderValue.From.Credential.password = Password

WebServiceLink.ReceiveMessageAsync(XmlString)

Regards


Gary.