asp.net ajax Partial rendering not working

I'm trying to do some ajax code but am failing miserably,the code below works

<asp:ScriptManager  ID="ScriptManager1" runat="server"></asp:ScriptManager>
<tr>
 <td>
  <asp:UpdatePanel ID="UpdatePanel1" runat="server">
   <ContentTemplate>
     <asp:Label ID="Label1" runat="server" Text="This is a label!"></asp:Label>
     <asp:Button开发者_StackOverflow社区 ID="Button1" runat="server" Text="Click Me" OnClick="Button1_Click" />                 
   </ContentTemplate>
  </asp:UpdatePanel>
 </td>
</tr>

But if i was to change the code like below,partial rendering of the page doesn't work

<asp:ScriptManager  ID="ScriptManager1" runat="server"></asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<tr>
     <td>
         <asp:Label ID="Label1" runat="server" Text="This is a label!"></asp:Label>
         <asp:Button ID="Button1" runat="server" Text="Click Me" OnClick="Button1_Click" />                 
</td>
</tr>
</ContentTemplate>
</asp:UpdatePanel>

Could someone please look into the code and tell me if im doing something wrong

UpdatePanel generates a div. So put you table inside and it should be fine

OK Code #1

<tr>
  <td>
    <div />
  </td>
</tr>

Wrong Code #2

<table>
  <div>
    <tr>
      <td>
      </td>
    </tr>
  </div>
</table>

What you should do (put the whole table inside the UpdatePanel)

<div>
  <table>
    <tr>
      <td>
      </td>
    </tr>
  </table>
</div>