title: Problem with textbox inside updatepanel - not causing OnTextChanged event
body: <p>I have the following situation: I have a textbox inside an ajax updatepanel. Wherever the user types in the textbox I must display a message (different message that depends on the user typed data).  </p>
  
  <pre><code>     &lt;asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Always"&gt;
          &lt;ContentTemplate&gt;
              &lt;asp:TextBox ID="txtMyTexbox" runat="server" Width="500px" OnTextChanged="txtMyTexbox_TextChanged" AutoPostBack="true"&gt;&lt;/asp:TextBox&gt;
              &lt;br /&gt;
              &lt;asp:Label ID="lblMessage" runat="server" CssClass="errorMessage" Visible="false"&gt;Hello World&lt;/asp:Label&gt;
           &lt;/ContentTemplate&gt;
              &lt;Triggers&gt;
               &lt;asp:AsyncPostBackTrigger ControlID="txtMyTexbox" /&gt;
              &lt;/Triggers&gt;
        &lt;/asp:UpdatePanel&gt;
  </code></pre>
  
  <p>In server side I have written the following at page load</p>
  
  <pre><code>ScriptManager.GetCurrent(this).RegisterAsyncPostBackControl(txtMyTexbox);           
  </code></pre>
  
  <p>and the method like this</p>
  
  <pre><code>protected void txtMyTexbox_TextChanged(object sender, EventArgs e)
      {           
              if (.....)
              {
                  lblMessage.Visible = false;
              }
              else
              {
                  lblMessage.Visible = true;
              }            
      }
  </code></pre>
  
  <p>My problem now is that: when the user types in the textbox it doesn't cause OnTextChanged event.</p>
  
  <p>Am I missing something? </p>