Call to undefined function library()

Saya mempunyai masalah ketika menyimpan profil saya. Problemnya adalah sebagai berikut:

An uncaught Exception was encountered

Type: Error

Message: Call to undefined function library()

Filename: C:\xampp\htdocs\sisko\application\controllers\profile.php

Line Number: 39

Backtrace:

File: C:\xampp\htdocs\sisko\index.php

Line: 315

Function: require_once

Berikut saya sertakan code controller/profile.php

<?php

class Profile extends CI_Controller
{
	function __construct()
	{
		parent::__construct();
		$this->load->model('M_profile');
	}

	public function index()
	{
		$data = array('data_profile' => $this->M_profile->ambil_profile()->result_array(),);

		$this->load->view('template/header');
		$this->load->view('template/sidebar');
		$this->load->view('dashboard/profile', $data);
		$this->load->view('template/footer');
	}

	function tambah_profile(){
		$this->load->view('template/header');
		$this->load->view('template/sidebar');
		$this->load->view('dashboard/tambah_profile');
		$this->load->view('template/footer');
	}

	function simpan_profile(){
		$id_profile = '';
		$judul = $this->input->post('judul');
		$isi = $this->input->post('isi');

		$config['max_size']=2048;
		$config['allowed_types']="jpg|jpeg|png";
		$config['remove_spaces']=TRUE;
		$config['overwrite']=TRUE;
		$config['upload_path']=FCPATH.'tentang';

		$this->load-library('upload');
		$this->upload->initialize($config);

		$data = $this->upload->do_upload('gambar');
		$data_image = $this->upload->data('file_name');
		$location = 'tentang/';
		$pict = $location-$data_image;

		$data = array(
			'id_profile'=>$id_profile,
			'nama'=>$judul,
			'isi'=>$isi,
			'gambar'=>$pict
		);

		$this->M_profile->simpan('profile', $data);
		$this->session->set_flashdata('sukses', "div class='alert alert-success alert-block'> <a class='close' data-dismis='alert' href='#'>x</a><h4 class='alert-heading'>Sukses!</h4>Data berhasil disimpan!</div>");
		redirect('profile');
	}

}

?>

Bagaimana cara memperbaikinya? Terima kasih sebelumnya.