Question

I did everything correct and its not showing me any error. I just want to allow user to enter numbers but its allowing all the characters.
Here is my source

<asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        <asp:FilteredTextBoxExtender ID="FilteredTextBoxExtender1" runat="server" TargetControlID="TextBox1" FilterType="Numbers">
        </asp:FilteredTextBoxExtender>
        <asp:Label ID="Label1" runat="server" Text="Phone No"></asp:Label>
&nbsp;<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

Answer 1

You should use a ToolkitScriptManager instead of a ScriptManager

You could also try ValidChars instead of FilterType

<asp:FilteredTextBoxExtender ID="FilteredTextBoxExtender1" runat="server" 
                             TargetControlID="TextBox1" ValidChars="0123456789.,">
</asp:FilteredTextBoxExtender>