[Library] upload error

[eluser]Unknown[/eluser]
Hi, i have problems uploading files with upload library, i did all what described in the docs, and also the script work on local server,but in the distant server the form is displayed and upload_path errors are displayed if there is a one.the problem was a blank page win clicking on the upload button.
there are my scripts:
controller : upload.php

Code:

class Upload extends CI_Controller
{
  function __construct()
{
  parent::__construct();
  
  $this->load->helper(array('url'=>'assets'));
  $this->load->database();

  $this->layout->set_titre("");
  $this->layout->ajouter_css(MY_STYLES);
}

  function index()
{
     redirect(base_url().'index.php/home');
}

  function do_upload($ann_id=0,$g_num_serie=0)
{
        
   if($this->session->userdata('usr_id') == NULL )
   redirect(base_url().'index.php/membres/connexion');

         $d = $this->annonces_model->get_annonce(array('annonce_id' => $ann_id));
  $annonce = $d->row();
  $num_serie = $annonce->num_serie_ann;
  $nb_images_charges = $annonce->annonce_nb_img;
  $erreur = false;
  $data = array();
  $data['error'] = "";
  $cat = $this->gen_fonctions->cat_name($annonce->annonce_cat_id);
  $data['cat'] = $cat;
  $data['annonce'] = $annonce;
  //write_file('assets/test_file', 'ann_id :'.$ann_id.' | num serie(vrai):'.$num_serie.'  | nserie:'.$g_num_serie.'  | annonce:'.$annonce);
    if($annonce == NULL OR empty($annonce) OR $num_serie != $g_num_serie)
   {
      $data['error'] = "Cette annonce n'exite pas !<br/>";
   $erreur = true;
   }
    if($nb_images_charges >= 2)
   {
      $data['error'] .= "Vous avez déjà chargé deux images.<br/>Pour les modifier: Editez l'annonce et cliquez sur modifier images.";
   $erreur = true;
   }
    
        
      //s'il y a une erreur
   if($erreur)
  {
  
   $this->layout->views('head');
          $this->layout->views('menu_gauche');
                 $this->layout->views('upload_message', $data);
          $this->layout->view('footer');
  
   return;
  }
  
  $config['upload_path'] = 'assets/images';
  $config['allowed_types'] = 'gif|jpg|png';
  $config['max_size'] = '600';
  $config['max_width']  = '3000';
  $config['max_height']  = '3000';
  $config['file_name']  = $annonce->membre_id.'-'.$annonce->annonce_id;

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

   if($this->upload->do_upload())
  {
          $this->resize_image($this->upload->data(),$annonce);
          $data = array();
   $data['ann_id'] = $ann_id;
          $data['nserie'] = $g_num_serie;
   $this->layout->views('head');
          $this->layout->views('menu_gauche');
   $this->layout->views('upload_succes', $data);
   $this->layout->view('footer');
  
  }
   else
  {
   $data = array('error' => $this->upload->display_errors(),'ann_id' => $ann_id,
                 'cat' => $cat,'nserie' => $g_num_serie);

   $this->layout->views('head');
          $this->layout->views('menu_gauche');
                 $this->layout->views('upload_form', $data);
          $this->layout->view('footer');
  
        
  }
}
  public function resize_image($img_data,$annonce,$insert=true)
{
         }
}

View : upload_form.php

Code:

<?php echo $error;?>
    <?php echo form_open_multipart(base_url().'index.php/upload/do_upload/'.$ann_id.'/'.$nserie);?>
       <input type="file" name="userfile" size="20" />
       <br /><br>
       &lt;input type="submit" value="upload" /&gt;

    &lt;/form&gt;

Also the redirect() function work in some pages but not in others.
Thanks for any help .

When i changed: define('ENVIRONMENT', 'production'); TO define('ENVIRONMENT', 'development'); in index.php

I received this error :

Code:

A PHP Error was encountered
Severity: Warning
Message: escapeshellarg() has been disabled for security reasons
Filename: libraries/Upload.php
Line Number: 1066