WSDL-based requests generate NS_ERROR_UNEXPECTED

I am trying to use the WSDL proxy mechanism to access one of the
sample services that comes with the Apache Axis distribution. The
service in question is pretty basic (just echo a string back). The
proxy seems to get created OK (a good indication there is no problem
retrieving the WSDL) but attempts to use the proxy to invoke the
service generate a NS_ERROR_UNEXPECTED exception:

  The src code is below. The point where the exception is thrown is
the line "gProxy.serviceMethod(aName);"  As best I can tell the code
follows the guidelines in the Jun 2003 article "Accessing Web Services
In Netscape 7.1/Mozilla 1.4 Using WSDL Proxying".

Any suggestions would be appreciated. 

Thanks

     Larry


var gProxy = null;
function executeSvc(){
  var aName = document.getElementById('inputValue').value;
  if (!gProxy) {
    var listener = {
      // gets called once the proxy has been instantiated
      onLoad: function (aProxy)
      {
        gProxy = aProxy;
        gProxy.setListener(listener);
        requestSvc(aName);
      },

      // gets called if an error occurs
      onError: function (aError)
      {
        alert("An error has occured: " + aError);
      },
      // callback function is hardcoded to {methodname}Callback
      serviceMethodCallback : function (aResult)
      {
        alert("Entered callback OK");
        document.getElementById("results").innerHTML = aResult;
      }
    };        
        createProxy(listener);
      } else {
        requestSvc(aName);
      }
    }

function createProxy(aCreationListener) {
   try {
       var factory = new WebServiceProxyFactory();
       
factory.createProxyAsync("http://localhost:8080/axis/services/MyService?wsdl";,
"MyService", "", true, aCreationListener);
       alert("Create proxy OK");
       }
  catch (ex) {
      alert("Failed to create proxy:" + ex);
      }
}

function requestSvc(aName){
  if (gProxy) {
    alert("Calling proxy with string ["+aName+"]");
    gProxy.serviceMethod(aName);
  } else {
    alert("Error: Proxy set up not complete!");
  }
}