Codeigniter ajax请求500内部服务器错误

Question

<script type="text/javascript">
    $(window).load(function(){
         $(".button_next a ").click(function(){
             var cct = $("input[name=syncrypts]").val();

             $.ajax({
                 url:"<?php echo base_url(); ?>index.php?customer/product/import", //Server script to process data
                 type: "POST",
                 data: { 'csrf_token_name': cct },
                 error: function (err) {
                     console.log("AJAX error in request: " + JSON.stringify(err, null, 2));
                 },
                 success: function(response){
                      alert("ok");     
                  }
             });
         });
    });
</script>

<?php echo form_open(base_url() . 'index.php?customer/product/import', array(
                'enctype' => 'multipart/form-data', 
                'class' => 'uk-form-stacked',
            ));

    ?>
            <input type="hidden" name="<?php echo $this->security->get_csrf_token_name(); ?>" value="<?php echo $this->security->get_csrf_hash(); ?>">
<?php echo form_close() ?>

代码不起作用。我同样有500个内部服务器错误。为什么？我在config.php中启用了csrf。我读的帖子是http://aymsystems.com/ajax-csrf-protection-codeigniter-20