jQuery .load和Session ID不同步？

I want to load my content dynamically. It contains php with session variables. I suppose that php works great, but the session variables are not accessible. There is everything wrong with my session_id:

index.php:

<?php 
$session_name = 'sec_session_id';   
$secure = SECURE;

$httponly = true;

if (ini_set('session.use_only_cookies', 1) === FALSE) {
header("Location: ../error.php?err=Could not initiate a safe session (ini_set)");
    exit();
}

$cookieParams = session_get_cookie_params();
session_set_cookie_params($cookieParams["lifetime"],
    $cookieParams["path"], 
    $cookieParams["domain"], 
    $secure,
    $httponly);

session_name($session_name);
session_start();           
session_regenerate_id(); 
?>

<div class="sidebar">
<ul id="nav">
  <li><a class="selected" href="#" data-target="page1">Dashboard</a></li>
  <li><a  href="#" data-target="page2">Pages</a></li>

</ul> 
</div>
<?php echo session_id(); Print_r ($_SESSION);  ?>
<div class="content" id="main-content">
<?php 
include('pages/page1.php'); 
?>

My Javascript:

<script>
  $(document).ready(function(){
    // Set trigger and container variables
    var trigger = $('#nav li a'),
        container = $('#main-content');

    // Fire on click
    trigger.on('click', function(){
      // Set $this for re-use. Set target from data attribute
      var $this = $(this),
        target = $this.data('target');  

                if (!$this.hasClass("selected")) {
                        $("#nav li a").removeClass("selected");
                        $this.addClass("selected");

                }
                else {
                    event.preventDefault();
                }

      // Load target page into container
      container.load('pages/' + target + '.php');

      // Stop normal link behavior
      return false;
    });
  });
</script>

And my loading content php file:

<?php 
session_start();
echo session_id(); 
Print_r ($_SESSION); 
echo ' php works'; 
?>

If I refresh my index.php at first everything loads normally. Ouput:

fodnkd14c3l4jkeunlakg81he5 Array ( [user_id] => 2 )

fodnkd14c3l4jkeunlakg81he5 Array ( [user_id] => 2 ) php works

If I load my page1.php via jquery load, i get this output:

fodnkd14c3l4jkeunlakg81he5 Array ( [user_id] => 2 )

ti7eqnmrrjmeckg5tln3ml2c83 Array ( ) php works

It looks like the session change in page1.php, after jQuery .load. Without session_regenerate_id(); it still does not work. How can I fix this?