Hi Ilya,
I don't know why. But the extended functions don't work.
I have to add the SOAP header "[SoapHeader("Lattice_SecurityHeader", Direction = SoapHeaderDirection.InOut)]" to the functions got from a Reference.cs file, which is auto-added when adding the service "https://secure.eloqua.com/API/1.2/Service.svc?wsdl" into Web References.And then, It works. Maybe the service makes me to work in this way.
Thank you very much!
Best Regards,
Biao