you are updating update panel conditional.
Please specify
UpdateMode="Conditional"
.
Make sure that you have use script manager.
You whole code will look like this.
<asp:ScriptManager ID="ScriptManager1" runat="server" />
<asp:UpdatePanel ID="up4" UpdateMode="Conditional" runat="server">
<ContentTemplate>
........
</ContentTemplate>
</asp:UpdatePanel>