Multi upload

I'm trying to create a control for upload multiple files

My controll:

PHP Code:

public function do_upload($path, $subpath) {
    $files = $_FILES['file']; $file ['file']=array();
    $num_file = count($_FILES['file']['name']);
    echo $path;
    for ($i = 1; $i <= $num_file; $i++) {
      if (isset($files[$i])) {
       $this->_CI->session->set_userdata(array('filename' => $files['name'][$i]));
       $this->load->library('upload', $this->set_upload_options());
       $this->upload->initialize($this->set_upload_options());
       chmod($path, 0777); chmod($subpath, 0777);
       $this->upload->do_upload($files[$i]);
       $error = array('error' => $this->upload->display_errors());
       foreach ($error as $errore)
        echo 'Errore: '.$errore;
       }
    }
}
 public function set_upload_options(){
 // upload an image options
  $image ='gif|jpg|png|GIF|JPG|PNG';
  $config['upload_path'] = $this->session->userdata('subdir');
  $config['allowed_types'] = $image;
   $config['overwrite'] = TRUE;
   if (!empty($this->session->userdata('filename'))) {
      $config['file_name'] = $this->session->userdata('filename');
    }
    $config['max_size'] = 100;
    $config['max_width'] = 1024;
    $config['max_height'] = 768;
    $config ['encrypt_name'] = TRUE;

    return $config;
    } 


View

PHP Code:

....
....
.....
<?php echo form_open_multipart('upload');?>
<?php echo form_upload('file[]','','multiple'); ?>
<input type="submit" value="upload" />

</form> 


I do not receive any error, but the file does not load

I do not know what to think.

Help me.

Thank you