simple node-soap (node.js) web service

I am trying to create a simple web service in node-js using node-soap. I have followed the example in the node-soap page here https://github.com/vpulim/node-soap

I am comsuming the web service in a visual studio project and it is allowing me to reference the web service and create the object ok in the project. When trying to call the sayHello method however I get an error complaining about the response not being 'text/xml' which is due to the error below.

Am I setting up the server file wrong or is my wsdl incorrect?

Here is my wsdl file

<?xml version="1.0"?>
<definitions name="HelloService"
   targetNamespace="http://localhost:8000/wsdl/HelloService.wsdl"
   xmlns="http://schemas.xmlsoap.org/wsdl/"
   xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
   xmlns:tns="http://localhost:8000/wsdl/HelloService.wsdl"
   xmlns:xsd="http://www.w3.org/2001/XMLSchema">

   <message name="SayHelloRequest">
      <part name="firstName" type="xsd:string"/>
   </message>
   <message name="SayHelloResponse">
      <part name="greeting" type="xsd:string"/>
   </message>

   <portType name="Hello_PortType">
      <operation name="sayHello">
         <input message="tns:SayHelloRequest"/>
         <output message="tns:SayHelloResponse"/>
      </operation>
   </portType>

   <binding name="Hello_Binding" type="tns:Hello_PortType">
   <soap:binding style="rpc"
      transport="http://schemas.xmlsoap.org/soap/http"/>
   <operation name="sayHello">
      <soap:operation soapAction="sayHello"/>
      <input>
         <soap:body
            encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"
            namespace="urn:examples:helloservice"
            use="encoded"/>
      </input>
      <output>
         <soap:body
            encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"
            namespace="urn:examples:helloservice"
            use="encoded"/>
      </output>
   </operation>
   </binding>

   <service name="Hello_Service">
      <documentation>WSDL File for HelloService</documentation>
      <port binding="tns:Hello_Binding" name="Hello_Port">
         <soap:address
            location="http://localhost:8000/SayHello" />
      </port>
   </service>
</definitions>

And here is my server file.

var fs = require("fs");
var soap = require('soap');
var http = require('http');

function start() {  

    var myService = {
        Hello_Service: {
            Hello_Port: {
                sayHello: function(args) {
                    return {
                        firstName: args.name
                    };              
                }              
            }
        }
    }

    xml = fs.readFileSync('wsdl/HelloService.wsdl', 'utf8'),
    server = http.createServer(function(request,response) {
        //response.end("404: Not Found: "+request.url)
        response.end(xml);      
    });

    server.listen(8000);
    var s = soap.listen(server, '/SayHello', myService, xml);

    s.log = function(type, data) {
        // type is 'received' or 'replied'
        console.log(type);
        console.log(data);
    };

}

exports.start = start;

And here is the error I get from the soap logging. Am I using the wrong name for the function?

info
Handling POST on /SayHello
info
Attempting to bind to /SayHello
info
Trying Hello_Port from path /SayHello
error
TypeError: undefined is not a function
    at Server._executeMethod (C:\Users\rnewman\node_modules\soap\lib\server.js:2
41:16)
    at Server._process (C:\Users\rnewman\node_modules\soap\lib\server.js:187:10)

    at IncomingMessage.<anonymous> (C:\Users\rnewman\node_modules\soap\lib\serve
r.js:103:14)
    at IncomingMessage.emit (events.js:92:17)
    at _stream_readable.js:938:16
    at process._tickCallback (node.js:419:13)

Thanks,

Robert