WHERE´S THE ValidatorCalloutExtender?

Portuguese Question
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Estou tentando chamar um ValidatorCalloutExtender a partir de um CustomValidator, alguém aqui já fez isso? Isso é possível? Pois no meu exemplo abaixo isso não funciona.
English Question
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I can try to call ValidatorCalloutExtender from a CustomValidator, but it´s not work. It´s possíble? My example doesn´t work. PLEASE HELP ME!
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teste.aspx
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1 <%@ Page Language="C#" AutoEventWireup="true" CodeFile="teste.aspx.cs" Inherits="teste" %>
2
3 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
4
5 <html xmlns="http://www.w3.org/1999/xhtml" >
6 <head runat="server">
7 <title>Untitled Page</title>
8 </head>
9 <body>
10 <form id="form1" runat="server">
11 <asp:scriptmanager ID="Scriptmanager1" runat="server"></asp:scriptmanager>
12 <div>
13 <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
14
15 <asp:CustomValidator ID="CustomValidator1" ControlToValidate="TextBox1" runat="server" ErrorMessage="weadsasdsa" OnServerValidate="CustomValidator1_ServerValidate"></asp:CustomValidator>
16 <ajaxToolkit:ValidatorCalloutExtender ID="ceUsuarioNome" TargetControlID="CustomValidator1" runat="server"></ajaxToolkit:ValidatorCalloutExtender>
17
18 <asp:Button ID="Button1" runat="server" Text="Button" />
19 </div>
20 </form>
21 </body>
22 </html>
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teste.aspx.cs
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1 using System;
2 using System.Data;
3 using System.Configuration;
4 using System.Collections;
5 using System.Web;
6 using System.Web.Security;
7 using System.Web.UI;
8 using System.Web.UI.WebControls;
9 using System.Web.UI.WebControls.WebParts;
10 using System.Web.UI.HtmlControls;
11
12 public partial class teste : System.Web.UI.Page
13 {
14 protected void Page_Load(object sender, EventArgs e)
15 {
16
17 }
18 protected void CustomValidator1_ServerValidate(object source, ServerValidateEventArgs args)
19 {
20 if(TextBox1.Text == "janis"){
21 args.IsValid = true;
22 }else{
23 args.IsValid = false;
24 }
25 }
26 }
27