Another "PageMethods is Undefined" error

Hi,
When viewing the following article - http://www.singingeels.com/Articles/Using_Page_Methods_in_ASPNET_AJAX.aspx - i've tryed to build a similar example but I'm having that same error - PageMethods is undefined -  and don't know how to solve it. Can you please help me? Here is my code:
 
User Control Code:
<%@ Control Language="C#" AutoEventWireup="true" CodeFile="UCTestemunhos.ascx.cs" Inherits="UserControls_UCTestemunhos" %>

<script language="javascript" type="text/javascript">

function SendForm() {
   var name = $get("NameTextBox").value;
   var email = $get("EmailTextBox").value;
   var message = $get("MessageTextBox").value;

   PageMethods.SendForm(name, email, message,
       OnSucceeded, OnFailed ...