Atlas to AJAX conversion problem with delegate. Need help.

I'm having trouble with the sample below since moving from Atlas to AJAX.
I've done a LOT of research with prototypes and delegates, but I can't get
this simple, "class-like" example to work in AJAX as it did in Atlas.
Any help greatly appreciated. Thanks in advance.

============ASPX PAGE=============

<%@dotnet.itags.org. Page Language="vb" AutoEventWireup="false" CodeBehind="test.aspx.vb" Inherits="WebApplication1.test" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
</head>
<body>
<form id="form1" runat="server">
<asp:ScriptManager runat="server" ID="ScriptManager1">
<Services>
<asp:ServiceReference Path="WS1.asmx" />
</Services>
</asp:ScriptManager>
<input type='button' value='Click me' id='myButton' onclick='doThis(778899)' />
</form>
</body>
</html>

<script type="text/javascript">

function doThis( MyNumber ){

var tmpOjb = new MySampleClass( MyNumber );
tmpOjb._StartMyFunction();
tmpOjb = null;

}
MySampleClass = function( MyNumber )
{
this._MyNumber = MyNumber;

this._StartMyFunction = function()
{
// This WORKS, but with asyncronous call...
// ... this._MyNumber is lost when _MyReturnHandler is run
/* */
WebApplication1.WS1.HelloWorld(
this._MyNumber,
this._MyReturnHandler);
/* */

// This DOES NOT WORK anymore, but DID with Atlas..
// How can I get this to work again??
/*
WebApplication1.WS1.HelloWorld(
this._MyNumber,
{onMethodComplete: Function.createDelegate(this, this._MyReturnHandler)});
*/
}

this._MyReturnHandler = function(result)
{
alert(result + "::::" + this._MyNumber);
}
};

</script>

============ASMX PAGE=============
Imports System.Web
Imports System.Web.Services
Imports System.Web.Services.Protocols
Imports System.Text
Imports System
Imports System.Data
Imports System.Data.SqlClient
Imports System.ComponentModel

<System.Web.Services.WebService(Namespace:="http://tempuri.org/")> _
<System.Web.Services.WebServiceBinding(ConformsTo:=WsiProfiles.BasicProfile1_1)> _
<System.Web.Script.Services.ScriptService()> _
<ToolboxItem(False)> _
Public Class WS1
Inherits System.Web.Services.WebService

<WebMethod()> _
Public Function HelloWorld(ByVal myNumber As String) As String
Return "Hello World [" & myNumber & "]"

End Function

End Class

The userContext is available for this purpose.

<script type="text/javascript">

function doThis( MyNumber ){

var tmpOjb = new MySampleClass( MyNumber );
tmpOjb.StartMyFunction();
tmpOjb = null;

}

MySampleClass = function(myNumber) {
this._myNumber = myNumber;
}

MySampleClass.prototype = {
StartMyFunction : function() {
var userContext = "Here is some text. This can be a JSON object too";
WebService.HelloWorld(
this._myNumber,
this._OnSucceed,
this._OnFail,
userContext);
},

_OnSucceed : function(result,userContext)
{
alert(result + "::::" +userContext);
},

_OnFail : function(error) {
alert(error);
}
}

</script>

http://ajax.asp.net/docs/ClientReference/Sys.Net/WebRequestClass/WebRequestUserContextMethod.aspx

Thanks Raj! That saved me a lot of time.
I wish I submitted the question earlier.

Thanks again.