CodeIgniter from another class

[eluser]consigliere[/eluser]
I tried and PHP throws this error:

Fatal error: Call to a member function library() on a non-object in Vehicles.php on line

Here are my files based on http://codeigniter.com/wiki/Calling_CI_m...de_script/

config_constants.php

Code:

<?php

if( ! $system_folder)
    $system_folder = "system";

if( ! $application_folder)
    $application_folder = "application";

if (function_exists('realpath') AND @realpath(dirname(__FILE__)) !== FALSE)
{
    $system_folder = str_replace("\\", "/", realpath(dirname(__FILE__))).'/'.$system_folder;
}


define('EXT', '.'.pathinfo(__FILE__, PATHINFO_EXTENSION));
define('FCPATH', __FILE__);
define('SELF', pathinfo(__FILE__, PATHINFO_BASENAME));
define('BASEPATH', $system_folder.'/');

if (is_dir($application_folder))
{
    define('APPPATH', $application_folder.'/');
}
else
{
    if ($application_folder == '')
    {
        $application_folder = 'application';
    }

    define('APPPATH', BASEPATH.$application_folder.'/');
}

if ( ! defined('E_STRICT'))
{
    define('E_STRICT', 2048);
}

?>

ci_model_remote_open.php

Code:

<?php

require_once('config_constants.php');

require(BASEPATH.'codeigniter/Common'.EXT);

set_error_handler('_exception_handler');
set_magic_quotes_runtime(0); // Kill magic quotes

$CFG     =& load_class('Config');
$LANG    =& load_class('Language');

if (floor(phpversion()) < 5)
{
    load_class('Loader', FALSE);
    require(BASEPATH.'codeigniter/Base4'.EXT);
}
else
{
    require(BASEPATH.'codeigniter/Base5'.EXT);
}

// instantiate a "fake" controller
$CI = load_class('Controller');

require_once(BASEPATH.'libraries/Form_validation'.EXT);

?&gt;

Vehicles.php

Code:

<?php

class Vehicles
{
    function __construct()
    {
        require_once("deca/utils/CodeIgniter_1.7.2/ci_model_remote_open.php");
        require_once("deca/utils/CodeIgniter_1.7.2/system/libraries/Form_validation.php");      
    }
    
    function sendCommands($param) {
        if (isset($_SESSION['USER_PWD'])) {
                        
            // CodeIgniter Code
            $system_folder = "CodeIgniter/system";
            $CI->load->library('form_validation');
            
            if ($CI->form_validation->run() == FALSE)
            {
                return "ERROR";
            }
            else
            {
                return "TRUE";
            }            
            
    }
        
    function __destruct()
    {
      $this->DB->close();
    }
}

?>