Captcha in CI

[eluser]cinewbie81[/eluser]
I've found this link in order to works on captcha - http://codeigniter.com/wiki/captcha/

The thing is i dont want to modify anything on my db structure ..

then i found this : http://ellislab.com/forums/viewthread/61678/

So i do

Code:

$this->load->helper('captcha');
            
        // create the captcha-config
        $aCaptchaCfg = array(
            //'word'          => 'myrandomword',    //default: random()
            'length'        => 6,                         //default: 5
            'img_path'   => './captcha/',   //no default !
            'img_url'       => site_url().'captcha/',  // no default!
            'font_path'  => './system/fonts/', // default: ./system/fonts/
            'fonts'         => array('texb.ttf'), // default: texb.ttf
            'font_size'     => 25,      // default: 18
            'img_width'  => '180',  // default: 170
            'img_height' => '60',   // default: 60
            'expiration' => 7200 // default: 7200
        );
            
        // get captcha-stuff
        $aCaptcha = create_captcha($aCaptchaCfg);
        print_r($aCaptcha); exit;

When i print_r($aCaptcha) and it return me nothing ... noted that i follow exactly as mentioned in the link