ReCAPTCHA library - ignited

[eluser]cellulit[/eluser]
Guys;

I feel numb. really. It seems to be so easy to incorporate recaptcha using this excellent library and I'm failing :\
Basically, I can't get the code validated. I can generate it, it gets validated against "required" condition, but not against the custom validation rule. Actually it always gets validated and returns "true". Any ideas?

the part of the controller...

Code:

// processing the registration form
    function regInsert()
    {
        $this->form_validation->set_rules('password','Password','trim|required');
        $this->form_validation->set_rules('email','Email','trim|required|valid_email|unique[users.email]');
        $this->form_validation->set_rules('name','Name','trim|required');
        $this->form_validation->set_rules('recaptcha_response_field','Captcha','required|callback_captcha_check');
        
        if ($this->form_validation->run() == FALSE)
        {
            $data['heading']="the following errors occured:";
            $data['recaptcha']=$this->recaptcha->get_html();
            $this->load->view('users_register_view',$data);
        }
        else
        {
            $this->db->insert('users',$_POST);
            echo 'cool! try to login now!';
        }
    }
    
    // checking captcha
    function check_captcha($val)
    {
      if ($this->recaptcha->check_answer($this->input->ip_address(),$this->input->post('recaptcha_challenge_field'),$val))
      //if ($this->recaptcha->isvalid)
      {
        return TRUE;
      }
      else
      {
        $this->form_validation->set_message('check_captcha',$this->lang->line('recaptcha_incorrect_response'));
        return FALSE;
      }
    }

By the way... Why there's $val variable used in the custom function? I can't see it passed in the validation rules (in a demo file).

Thanks in advance!