title: Error: Extender controls may not be registered before PreRender
body: <p>I am trying to add Ajax Controls to my *.aspx pages.</p>
  
  <p>I just added </p>
  
  <pre><code>&lt;asp:CalendarExtender TargetControlID="UserName" runat="server"&gt;
  &lt;/asp:CalendarExtender&gt;
  </code></pre>
  
  <p>And getting the error. Any solution?</p>
  
  <p>Please don't tell me to read the similar questions on stackoverflow.com. None worked for me.</p>