$_POST['stock_id'] = get_global_stock_item();
echo "<center>" . _("Select an item to display its parent item(s).") . " ";
-stock_items_list('stock_id', $_POST['stock_id'], false, true);
+echo stock_items_list('stock_id', $_POST['stock_id'], false, true);
echo "<hr></center>";
set_global_stock_item($_POST['stock_id']);