Ajax mulit handle slider not working

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ASP.NET

Ajax

Hi
I have tried using Ajax multihandle slider extender and I used the following code

<asp:TextBox ID="slider2" runat="server"></asp:TextBox>
 <asp:TextBox ID="slider2_boundControl1" runat="server" Text="25" Style="display: none;"></asp:TextBox>
<asp:TextBox ID="slider2_boundControl2" runat="server" Text="100" Style="display: none;"></asp:TextBox>
<ajaxToolkit:MultiHandleSliderExtender ID="SliderExtender2"  runat="server" TargetControlID="slider2"
BehaviorID="SliderExtender2">
<MultiHandleSliderTargets>
<ajaxToolkit:MultiHandleSliderTarget ControlID="slider2_boundControl1" />
<ajaxToolkit:MultiHandleSliderTarget ControlID="slider2_boundControl2" />
</MultiHandleSliderTargets>
</ajaxToolkit:MultiHandleSliderExtender>

and and I am encountering an exception as mentioned below

Microsoft JScript runtime error: Sys.InvalidOperationException: Type Sys.Extended.UI.SliderOrientation has already been registered. The type may be defined multiple times or the script file that defines it may have already been loaded. A possible cause is a change of settings during a partial update.

Can anyone help me on what has to be done.

Thanks in advance