title: MessageBox Inside Updatepanel is not displayed
body: <p>The Messagebox code in c# i've used is the following code,which is call conditionally based on my requirement.It works fine in all cases except when the Ajax update panel is used.
  For example i would like to prompt the user if no check box is selected in a gridview,with 
  appropriate message,The code is executed but no message box is displayed </p>
  
  <pre><code> public static void MessageBox(string message, Page page)
      {       
          if (!string.IsNullOrEmpty(message))
          {
              Label lbl = new Label();
              lbl.Text = "&lt;script type=\"text/javascript\" language=\"javascript\"&gt;" + "alert('" + message + "'); " + "&lt;/script&gt;";
              page.Controls.Add(lbl);
          }
      }
  </code></pre>