Fatal error: Call to a member function library() on a non-object.

[eluser]Unknown[/eluser]
I'm not sure how to solve this codeigniter error.

Error: Fatal error: Call to a member function library() on a non-object.

Controller

Code:

public function index()
{
  $this->load->helper('url');
  
  $this->load->library('header');
  
  $data['title']    = $this->header->get_page_name();
  $data['gutter_value']  = $this->header->get_gutter_value();
  $data['js_page']   = $this->header->get_js_page_file();
  $data['page']    = $this->header->page;
  $data['index_page']          = $this->header->index_page;
  $data['nav_names']   = $this->header->nav_names;
  $data['banner_img']  = $this->header->get_banner_img();
  
  $this->load->view('includes/header', $data);
  
  $this->load->view('about/about_view');
  
  $this->load->view('includes/footer');
}

Library File

Code:

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class Header{

var $page    = '';
var $index_page  = '';
var $nav_names  = array();
var $banner_imgs  = array();

public function __construct(){

  $this -> index_page = 'Writing';
  $this -> nav_names = array('Contact', 'About', 'Tools', 'Portfolio', 'Writing');
  
  if($_SERVER['PHP_SELF'] === '/index.php')
  {
   $this -> page = 'Writing';
  }
  else
  {
   $this -> page = end(explode(DIRECTORY_SEPARATOR, $_SERVER['PHP_SELF']));
  }
}

function get_page_name()
{
  $this->load->library('common');
  
  $page_names = $this->common->page_names();

  $title = (array_key_exists($this->page, $page_names) !== false) ? $page_names[$this->page]: '';

  if (array_key_exists($this->page, $page_names) !== false)
  {
   $title .= " | Jason Biondo";
  }
  
  return $title;
}

function get_banner_img()
{
  $banner_imgs = array('contact.jpg', 'about.jpg', 'tools.jpg', 'portfolio.jpg', 'writing.jpg');
  
  foreach($this->nav_names as $k => $name)
  {
   if(($this->page === strtolower($name)) OR ($this->uri->segment(1) === strtolower($name)))
   {
    $banner_img = $banner_imgs[$k];
   }
  }
  
  return isset($banner_img) ? $banner_img : 'writing.jpg';
}

function get_gutter_value()
{
  $gutter_values  = array('304', '228', '158', '82', '0');
  
  foreach($this->nav_names as $k => $name)
  {
   if(($this->page === strtolower($name)) OR ($this->uri->segment(1) === strtolower($name)))
   {
    $g_value = $gutter_values[$k];
   }
  }
  
  return isset($g_value) ? $g_value : 0;
}

function get_js_page_file()
{
  $page = $this->page;
  
  if (file_exists("./js/pages/${page}.js"))
  {
   $javascript = "[removed][removed]";
  }
  
  return isset($javascript) ? $[removed] FALSE;
}
}
/* End of file header.php */
/* Location: ./application/libraries/header.php */