script manager in asp.net with update panel

<form id="form1" runat="server" >
   <asp:ScriptManager ScriptMode="Release" ID="ScriptManager1" runat="server">
   </asp:ScriptManager>
 <asp:updatepanel id="UpdatePanel1" runat="server" xmlns:asp="#unknown">
        <contenttemplate>
                                           
                <asp:button id="Button1" runat="server" text="Validate" onclick="Button1_Click" />
<asp:label id="lbl" runat="server" />
 </contenttemplate>
</asp:updatepanel>

//in button click event
lbl.Text="this is example";