title: The OrderedDictionary is read only and cannot be modified
body: <p>Q:</p>
  
  <p>When i try the following code :</p>
  
  <pre><code> ((IOrderedDictionary)Session["keys"])[2] = objToUpdate.Note_title;
   ((IOrderedDictionary)Session["keys"])[3] = objToUpdate.Iscourse;
  </code></pre>
  
  <p>It throws an exception:</p>
  
  <blockquote>
    <p>The OrderedDictionary is read only and
    cannot be modified.</p>
  </blockquote>
  
  <hr>
  
  <p>My question:</p>
  
  <ul>
  <li>Why just read only?</li>
  <li>How to set my key in the session,fixing my problem?</li>
  </ul>
  
  <p><strong>EDIT:</strong></p>
  
  <p>I fill the <code>IOrderedDictionary</code> through this:</p>
  
  <pre><code>IOrderedDictionary keys = gv_courses.DataKeys[index].Values;
  
  Session["Keys"] = keys;
  </code></pre>