JSP :: Session Validate Is Not Working In Internet Explorer

I have a click button called log off , here once a user clicks it , task goes to logout servlet to end current user session . below is my code , I don't know why it works fine with mozilla firefox and google chrom but not working with internet explorer.

response.setHeader("Cache-Control","no-store"); //HTTP 1.1
response.setHeader("Pragma","no-cache"); //HTTP 1.0
response.setDateHeader ("Expires", 0);
HttpSession httpSession = request.getSession();

[Code] ....

here it goes fine to my index, but if I logged in again, I should enter a new session , but unfortunately this not happened in explorer , works fine with mozilla , and chroom.

I have also done in my index.jsp the check like below:

<%
if(session!=null){
session.setAttribute("validUser",null);
session.invalidate();
%>

just to erase whatever previous session . But why session exist on same page ! only in explorer , it makes me open new explorer for new user and that is what I don't want !