title: IE 11 Issue : Session getting null on Iframe postback...?
body: <p>I have a project with a login page and a navigator page containing <code>iframe</code> in it. All the other pages in the project are loading inside <code>iframe</code>.
  I am setting one session value to store userid from login page. After logging in, when I click on some pages which is loading inside <code>iframe</code> and then click on an asp button which is outside of <code>iframe</code> (in navigator page) my session value is getting null.</p>
  
  <p>When I searched in internet, I found that adding <strong>Privacy Preferences Project(P3P)</strong> header could solve the issue.So I added it in login page, navigator page and in pages which loads inside of <code>iframe</code> like the following:</p>
  
  <pre><code>private void Page_PreInit(object sender, System.EventArgs e){
  HttpContext.Current.Response.AddHeader ("p3p","CP=\"IDC DSP COR ADM DEVi TAIi PSA PSD IVAi IVDi CONi HIS OUR IND CNT\"");
  }
  </code></pre>
  
  <p>But still the same problem only with internet explorer 11. </p>
  
  <p>Why does this happen? Please share your valuable suggestions to fix it.</p>