Problem with ajax control

<asp:SliderExtender ID="SliderExtender1" runat="server"

            BehaviorID="Slider1"

            TargetControlID="Slider1"

            BoundControlID="Slider1_BoundControl"

             />

    <asp:TextBox ID="Slider1" runat="server"></asp:TextBox>

    <asp:TextBox ID="Slider1_BoundControl" runat="server"></asp:TextBox>