AJAX php sessions issue

Dear experts out there,

I am devellopping an AJAX application using php/mysql and javascript in following way:
1-
index.php initiating the session:
    session_start() ;
    with a search box, allowing user to choose the item he looks for with an ajax autosuggest
    and a div that will contain page2 with the results of the search -> onclick= call ajax function and load content into the div
2-
page2 (contained in the div) setting a value to a session variable:
    values of the search results and sets a php session like below:
if(isset($_GET['item']))
{
$_SESSION['item']=$_GET['item'];
}
    item has a value and when I make an echo $_GET['item'] or echo $_SESSION['item'] it shows up with the correct value
   has an include include('page2.1')
-2.1 INCLUDED INNCLUDED in page2
page 2.1 is included in page2: When doing an echo $_SESSION['item'], it returns the right value has a link that submits some values with my ajax function.

-3 --> PROBLEMS CALLING MY SESSION
This page is contained in a div is loaded through an AJAX request getting all the values from my ajax function is ok but when trying to do an echo $_SESSION['item'] it returns following error:
Notice: Undefined index: test

I don't get it... Same pages without AJAX functions work. Is there someone that understands what is happening?

I looked on the web and the only thing I saw is : Race Conditions issues, but if it was I would not get that error...