title: Textbox value remains empty in UpdatePanel
body: <p>I have a couple of update panels on my page as follows:</p>
  
  <pre><code>&lt;asp:UpdatePanel ID="UpdatePanel1" runat="server"&gt;
    &lt;Triggers&gt;
      &lt;asp:AsyncPostBackTrigger ControlID="Button1" /&gt;
    &lt;/Triggers&gt;
    &lt;ContentTemplate&gt;
      &lt;asp:TextBox ID="TextBox1" runat="server"&gt;&lt;/asp:TextBox&gt;
      &lt;asp:Button ID="Button1" runat="server" Text="Submit"&gt;&lt;/asp:Button&gt;
    &lt;/ContentTemplate&gt;
  &lt;/asp:UpdatePanel&gt;
  
  &lt;asp:UpdatePanel ID="UpdatePanel2" runat="server"&gt;
    &lt;ContentTemplate&gt;
      ...some more basic controls here...
    &lt;/ContentTemplate&gt;
  &lt;/asp:UpdatePanel&gt;
  </code></pre>
  
  <p>When I hit submit in UpdatePanel1, the value in the textbox is lost. I'm not sure if this is due to having two update panels on the same page or something else.</p>
  
  <p>UpdatePanel2 is where I'm trying to move the textbox value. But for the sake of testing the string, I've removed all my code and simply added a message box on my click event for Button1 to check if the string is being passed. Seems it is an empty string each time.</p>
  
  <p>I've tried setting <code>ChildrenAsTriggers</code> to both true and false, removed the triggers section, set the update panel's <code>enableviewstate</code> property to true, tried toggling between update modes, but nothing seems to be working.</p>
  
  <p>This probably might be a duplicate, but I've browsed through the posts related to this on here and on Google, but still haven't found any solutions.</p>
  
  <p>Any ideas?</p>