iframe designmode = "on" ie., in deep div

Question

I have "mypage.html" which contains

<div id = "more">
 <div id = "content">
  </div>
 </div>

  where <div id = "content"> contains another html page 
  I have accessed it using jquery in "mypage.html"
  the code is 

 $(document).ready(function(){
    $("#content_window").load("otherpage.html");   
}); 

where "otherpage.html" contains

<div id = "question>
  <div id = "box">
    <div id = "richtextare">
      <iframe id = "wysiwyg" name = "wysiwyg">
      </iframe>
     </div>
   </div>
 </div>

Where "Elements" is "DevTools" in chrome showing up the elements like this

<div id = "more">
 <div id = "content">
  <div id = "question>
   <div id = "box">
    <div id = "richtextare">
    <iframe id = "wysiwyg" name = "wysiwyg">
    </iframe>
   </div>
  </div>
  </div>
 </div>
</div>

Now how can i "on" the design mode of "iframe". When i use

 var richeditor = wysiwyg.document;
       richeditor.designMode = "on";

design mode is working in "otherpage.html" but it is not working in "mypage.html"