$_SESSION - creating a shopping cart? session not adding

[phpjaco]

got the following code: whats suppose to happen is that I get a POTST['listAll'] from flash. I then explode it by finding the commas in the POST string and convert this to an array.

I then add the array to the session array. This all works but the session does not keep adding, so when I add another page's products. The list is cleared and the Session get only added the new products?

i originally put a $latest .= in front of the array_push command but that didnt help.

any advise would be great 🙂 🙂

session_start();

   if (!session_is_registered($_SESSION['old_products'])) {
           session_register($_SESSION['old_products']);
	      $_SESSION['old_products'] = array();
    }
	if (!isset($latest)) {
	    $latest = array();
	}


if ($_POST['listAll']) {


   echo $_POST['listAll'] . '<br>';
   /************************************
	   INPUT FROM FLASH IS SUCCESSFULL
	  ***********************************/
  if (!$holder) {
  $holder = array();
  }

  $holder = array_unique(explode(',',$_POST['listAll']));

  /*******************************************
      NOW PUT ALL ITEMS INSIDE THE SESSION
   ******************************************/

  foreach ($holder as  $val) {
     if (array_unique($holder)) {
       array_push($_SESSION['old_products'],$holder);

 }
  } 

 foreach(latest as $val2) {
    echo $val2 . '<br>';
 }