[SOLVED] captcha not working

[eluser]zenixgrace[/eluser]
hi,

i'm a newbie in codeigniter
i'm use v 2.0.3

i try to use codeigniter captcha library

i got some error when i want to put in database

when i trace my code, i get a NULL value in my $cap['time'] and the others

here is my code controller

Code:

class Test extends CI_Controller {
        function __construct()
{
  parent::__construct();
  $this->load->library('testlib');
}

function index()
{  
    $data['cap'] = $this->testlib->setCaptcha();
           $this->load->view('home/index',$data);
}
}

here is my library code

Code:

class Testlib {
var $CI = NULL;

function __construct()
{
  $this->CI =& get_instance();
  $this->CI->load->library('encrypt');
}

function setCaptcha()
{
  $this->CI->load->helper('captcha');
  $vals = array(
   'word'       => random_string('alnum', 6),
   'img_path'   => $this->CI->config->item('captcha_path'),
   'img_url'    => $this->CI->config->item('captcha_url'),
   'font_path'  => './path/to/fonts/texb.ttf',
   'img_width'  => '140',
   'img_height' => 30,
   'expiration' => 3600 //one hour
  );
  $cap = create_captcha($vals);
  
  $data = array(
   'captcha_time' => $cap['time'],
   'ip_address'   => $this->CI->input->ip_address(),
   'word'         => $cap['word']
  );
  $query = $this->CI->db->insert_string('captcha', $data);
  $this->CI->db->query($query);
  
  return $cap;
}
}

i already set captcha path and url in my config.php

Code:

$config['captcha_path'] = './captcha/';
$config['captcha_url']  = $config['base_url'].'captcha/';

when i debug my code captcha didn't return anything..
$cap['time'] return NULL value
$cap['word'] return NULL value
and the image didn't show


is my code has wrong?
can someone explain me how can i fixed that?