codeigniter 2.0 problem with model

[eluser]kris10[/eluser]
I got an error on my model

Fatal error: Call to undefined method CI_Model::Model() in /home/cb/public_html/1/radiomotion/application/models/media_model.php on line 8

Code:

<?php
class Media_model extends CI_Model{

function Media_model()
    {
        // Call the Model constructor
        parent::Model();
    }

/*  =========== Ajout ========================= */
    function addMedia(){

              $data = array('med_titre' => $_POST['med_titre']
                    );
    
      $this->db->insert('media',$data);
    
    }
    
    
}


?>

line 8 is parent::Model();

What did I forget ?