Problems with using ajax toolkit in asp.net

Question

First I installed AjaxControlToolkit, run the "Install-Package AjaxControlToolkit" this command in the Package Manager Console. Then, I did add register AjaxControlToolkit at the top of the page and also in the web.config for the whole project. In between, I did go through some q&a like Ajax Toolkit ASP.NET (Visual Basic) Not Displaying Calendar. Unfortunately, my project still cannot integrated with AjaxControlToolkit and I got the error as below.

"Error 2 Unknown server tag 'ajaxToolkit:CalendarExtender'. C:\Users\admin\Documents\Visual Studio 2010\WebSites\testing\testing.aspx 8 ".

Thanks for reading and appreciate for any reply.

This is the message that I got from Package Manager Console and the coding attached below are testing.aspx and web.config .

PM> Install-Package AjaxControlToolkit 'AjaxControlToolkit 4.1.51116' already installed. testing already has a reference to 'AjaxControlToolkit 4.1.51116'.

testing.aspx

<%@ Register TagPrefix="asp" Namespace="AjaxControlToolkit" Assembly="AjaxControlToolkit"%>
<%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="testing.aspx.cs" Inherits="testing" %>

<asp:Content ID="Content1" ContentPlaceHolderID="main" Runat="Server">
    <asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
    <asp:TextBox ID="Date1" runat="server"></asp:TextBox>
    <ajaxToolkit:CalendarExtender ID="CalendarExtender1" runat="server" TargetControlID="Date1">
</ajaxToolkit:CalendarExtender>
</asp:Content>

web.config

<?xml version="1.0"?>
<!--
  For more information on how to configure your ASP.NET application, please visit
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->
<configuration>
  <connectionStrings>
    <add name="ConnectionString" connectionString="Data Source=navi.thegigabit.com;Persist Security Info=True;User ID=summerap;Password=summerap1" providerName="System.Data.SqlClient"/>
  </connectionStrings>
  <system.web>
    <customErrors mode="Off"/>
    <compilation debug="true">
      <assemblies>
        <add assembly="System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
        <add assembly="System.Web.Extensions.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.ServiceModel.Activation, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
        <add assembly="System.Runtime.Serialization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
        <add assembly="System.Web.ApplicationServices, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
        <add assembly="System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
        <add assembly="System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
        <add assembly="System.Configuration, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
        <add assembly="System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
        <add assembly="System.Xml, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
        <add assembly="System.Web.Services, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
        <add assembly="System.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
        <add assembly="System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
        <add assembly="System.Data.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
        <add assembly="System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
        <add assembly="System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
        <add assembly="System.ServiceModel.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
        <add assembly="System.Data.Services.Client, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
        <add assembly="System.Data.Services.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
        <add assembly="System.Data.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
        <add assembly="System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
        <add assembly="System.Web.DynamicData, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
        <add assembly="System.ComponentModel.DataAnnotations, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
        <add assembly="System.Web.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
        <add assembly="System.Xml.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
      </assemblies>
    </compilation>
    <pages>
      <controls>
        <add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add namespace="AjaxControlToolkit" assembly="AjaxControlToolkit" tagPrefix="asp" />
      </controls>
    </pages>

    <httpHandlers>
      <remove verb="*" path="*.asmx" />
      <add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
      <add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
      <add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" validate="false" />
    </httpHandlers>

    <httpModules>
      <add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
    </httpModules>

  </system.web>
</configuration>

Answer 1

The tag prefix is what you should be using to reference the controls, so you shouldn't be using "asp" as the tag prefix.

<add namespace="AjaxControlToolkit" assembly="AjaxControlToolkit" tagPrefix="ajaxToolkit" />