UpdatePanel in asp.net

<asp:UpdatePanel ID="Updatepnl1" runat="server" UpdateMode="Conditional" RenderMode="inline">
<ContentTemplate>
<asp:Panel ID="pnlhiddenimage" runat="server">
<b style="font-size:13px">Enjoy these unforgettable memories by clicking on  </b>
<asp:Image ID="img1" Height="500" Width="500" runat="server" Visible="false" ImageUrl="~/Images/image002.gif" />
</asp:Panel>

</ContentTemplate><Triggers>
<asp:AsyncPostBackTrigger ControlID="ddlcat" EventName="SelectedIndexChanged"></asp:AsyncPostBackTrigger>
</Triggers>
</asp:UpdatePanel>

<asp:DropDownList id="ddlcat" runat="server" AutoPostback=’true’  OnSelectedIndexChanged=’methodname’>
<asp:ListItem Value="0">test1</asp:ListItem>
<asp:ListItem Value="1"> test1</asp:ListItem>
</asp:DropDownList>