c#客户端向 PYTHON SOAPLIB+WEB.PY 通信问题

[fatlity]

现象：c#客户端获取不到服务器端的返回值，一直是null

c#客户端代码

            //添加web引用http://127.0.0.1:8080/hello.wsdl为WS
            WS.HelloService ws = new PYBETEST.WS.HelloService();
            WS.hello inp = new PYBETEST.WS.hello();
            inp.message = "me";
            WS.helloResponse re = ws.hello(inp);
            //re为null

python服务端代码

import web 
from soaplib.wsgi_soap import SimpleWSGISoapApp
from soaplib.service import soapmethod
from soaplib.serializers import primitive as soap_types

urls = ("/hello", "HelloService",
        "/hello.wsdl", "HelloService",
        )
render = web.template.Template("$def with (var)\n$:var")



class SoapService(SimpleWSGISoapApp):
    """Class for webservice """

    #__tns__ = 'http://test.com'

    @soapmethod(soap_types.String,_returns=soap_types.String)
    def hello(self,message):
        """ Method for webservice"""
        return "Hello world "+message



class HelloService(SoapService):
    """Class for web.py """
    def start_response(self,status, headers):
        web.ctx.status = status
        for header, value in headers:
            web.header(header, value)


    def GET(self):
        response = super(SimpleWSGISoapApp, self).__call__(web.ctx.environ, self.start_response)
        return render("\n".join(response))


    def POST(self):
        response = super(SimpleWSGISoapApp, self).__call__(web.ctx.environ, self.start_response)
        return render("\n".join(response))

app=web.application(urls, globals())

if __name__ == "__main__":
    app.run()

用python客户端可以取得返回值
python客户端代码

from soaplib.client import make_service_client
from testServer import HelloService

client = make_service_client('http://localhost:8080/hello', HelloService())
a= client.hello('me')
print a

#Hello world me

难道c#调用python的webservice需要什么特殊的方法吗?