ขอสอบถาม library File Upload Codeigniterครับ ไม่สามาถใช้งานบนHostได้ครับ

<?php

/*
*Tochange/thistemplate,/chooseTools | Templates
 * and open the template in the editor.
 */

/**
 * Description of admin_music
 *
 * @author Administrator
 */
class Upload extends CI_Controller{
    
    public function __construct() {
        parent::__construct();
    }
    public function index(){
        
        $this->load->view('admin/music_add', array('error' => '' ));
        
    }
    public function do_upload(){
        $config['upload_path'] = './upload/';
	$config['allowed_types'] = 'gif|jpg|png';
	$config['max_size']	= '10000';
	$config['max_width']  = '1024';
	$config['max_height']  = '1024';

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

	if ( ! $this->upload->do_upload())
	{
		$error = array('error' => $this->upload->display_errors());

		$this->load->view('admin/music_add', $error);
	}
	else
	{
		
                $data["img"] = $this->upload->data();  

		$this->load->view('admin/music_add_successful', $data);
                
        }
        
    }
}

?>