revisi code mu, di PHP 5.6 parent::__construct di hapus. Dan bagian config/hooks.php rubah bagian ini 'class' => 'Usertracking',

usertracking.php

<?php if(!defined('BASEPATH')) exit('No direct script access allowed');
/**
 * Usertracking Class
 *
 * @package		CodeIgniter
 * @subpackage	Hook
 * @category	Usertracking
 * @author		zhiephie
 */
class Usertracking {
		
		private $CI = null;
		public function __construct()
        {
            // parent::__construct(); //Remove in php5.6 +
			$this->CI =& get_instance();
			$this->CI->load->library('form_validation', 'session');
            $this->CI->load->helper('date');
			$this->CI->output->get_output();
        }
		
		public function idNum() 
		{
           $CI =& get_instance();
           $CI->db->select_max('id');
           $CI->db->order_by('id', 'DESC');
           $query = $CI->db->get('usertracking');
           $row = $query->result_array();
           $data['query'] = 1 + $row[0]['id'];
		   
		   return $data['query'];
		}
        public function log_activity() 
		{
                // We need an instance of CI as we will be using some CI classes
                $CI =& get_instance();
                $id_id  = $this->idNum();
                $data['id'] = $id_id;
                $data['userID'] = $CI->session->userdata('userID');
                // Next up, we want to know what page we're on, use the router class
                $data['section'] = $CI->router->class;
                $data['action'] = $CI->router->method;
                // We don't need it, but we'll log the URI just in case
                $data['activities'] = uri_string();
                // Lastly, we need to know when this is happening
                $data['times'] = date('Y-m-d H:i:s');
                       
                // And write it to the database
                $CI->db->insert('usertracking', $data);
        }
}