Update Panel empty

Hello,

I have an update panel in a table cell. Inside the update panel I have buttons and a multiview. Since I packed the label, buttons and the multiview in the update panel, the tablecell is an empty div. The DOM structure is

<div>

  <asp:table>

    <asp:tablerow>

       <asp:tablecell>

        <asp:scriptmanager id="scmMain" runat="server" />

        <asp:updatepanel id="uppMyPanel" runat="server">

           <asp:contenttemplate>

             <asp:label>

             <asp:button1>.... <asp:button n>

             <asp:multiview>  <asp:view> ...image <asp:view> ..... <asp:view> ...image <asp:view>

             </asp:multiview>

           </asp:contenttemplate>

          </asp:updatepanel>

         </asp:tablecell>

        <asp:tablecell>  an image logo displaying correctly </asp:tablecell>

      </asp:tablerow>

    </asp:table>

  </div>

This is what I have when I inspect the element:

<div id="head_menu"><table id="tblMenu" cellpadding="10" border="0" style="width:100%;"><tr id="tblRow2"><td id="tblCell5" align="center" valign="top" style="background-color:#FFBF00;width:70%;">       <script type="text/javascript">
//<![CDATA[
Sys.WebForms.PageRequestManager._initialize('scmMain', 'form1', ['tuppMyPanel',''], [], [], 90, '');
		//]]></script><div id="uppMyPanel"></div></td><td id="tblCell6" align="center" valign="top" style="width:30%;"><img id="imgLogo" src="Images/MyLogo.gif" style="border-width:0px;" /></td></tr></table>

I added the System.Web.Extensions assembly in the web.config file.

I inspected the element in Mozilla and in Chrome, there is absolutely no error. My cell is empty and yellow.

There is no css setting hidden property for the controls.

I found no forum with something similar...

This is in IIS7, .NET 4.0

<add assembly="System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>

Thank and regards,

Alex