Ajax forbidden 403

Hi at all , sorry for english , i have a problem with ajax in  this site 
http://preventivoamianto.altervista.org/...istrazione

i use ajax in several project but i cannot know why in this i haven't response :

i insert in config this: $config['csrf_exclude_uris'] = array('aziende/registrazione');


But i have not response.

This is the controller:

PHP Code:

     function get_province(){
            
            
        $csrf =  $this->security->get_csrf_hash();
        $this->output
                  ->set_content_type('application/json')
                  ->set_output(json_encode(array( 'csrf' => $csrf)));
           
         return  $this->location_model->get_province();
         
      } 


And this the model :

PHP Code:

function get_province(){
         
      $regioni_id=$this->input->post('regione');
      
      $query = $this->db->query("SELECT * FROM  province WHERE id_regione= $regioni_id  ORDER BY provincia asc");
      $res= '<option value="" selected="selected">-- seleziona --</option>';
         foreach($query->result() as $province){
         
         $id=$province->id;
         $provincia=$province->provincia;
         $res.= "<option value='$id'>$provincia</option>";
   
         }
         
         echo $res;
      }