Range Validators

I have one text box & a range validator

 <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

<asp:RangeValidator ID="RangeValidator1" runat="server"
            ControlToValidate="TextBox1" ErrorMessage="Wrong Value" MaximumValue="5"
            MinimumValue="3"></asp:RangeValidator>

but this is not working
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