Web service not found in javascript

Hi. I tried to create this by following the video at http://www.asp.net/learn/videos/video-7026.aspx where Joe Stagner created a simple web service that is called by Ajax. In the Button1_onclick() handler, javascript can't resolve the object "WebService1". Please have a look and see if there is anything wrong.

The exact error is "'WebService1' is undefined" in Button1_onclick().

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="AjaxTest._Default" %> <!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 runat="server"> <title></title> <script languag ...