Unknown server tag 'ajaxToolkit:ConfirmButtonExtender'.

I am getting the following error:


Parser Error
Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately.

Parser Error Message: Unknown server tag 'ajaxToolkit:ConfirmButtonExtender'.

Source Error:


Line 162:                                <td>
Line 163:                                    <asp:Button ID="Button2" runat="server" Text="Change" Enabled="False" />
Line 164:                                    <ajaxToolkit:ConfirmButtonExtender ID="ConfirmButtonExtender1" runat="server" TargetControlID="Button2"
Line 165:                                        ConfirmText="Are you sure you want to apply these changes?"/>
Line 166:                                </td>
 




My Webconfig Assemblies


                  <assemblies>
                        <add assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
                        <add assembly="System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
                        <add assembly="System.Web.Extensions.Design, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
                        <add assembly="System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>

                        <add assembly="CrystalDecisions.CrystalReports.Engine, Version=10.2.3600.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"/>
                        <add assembly="CrystalDecisions.ReportSource, Version=10.2.3600.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"/>
                        <add assembly="CrystalDecisions.Shared, Version=10.2.3600.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"/>
                        <add assembly="CrystalDecisions.Web, Version=10.2.3600.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"/>
                        <add assembly="CrystalDecisions.ReportAppServer.ClientDoc, Version=10.2.3600.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"/>
                        <add assembly="CrystalDecisions.Enterprise.Framework, Version=10.2.3600.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"/>
                        <add assembly="CrystalDecisions.Enterprise.InfoStore, Version=10.2.3600.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"/>
                        <add assembly="System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
                        <add assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
                        <add assembly="System.Web.Extensions.Design, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
                  </assemblies>

Is there anything that I am missing here, perhaps the Web.Extensions versions are wrong or I am missing something else from the web.config.