protected function GenerateCaptcha()
    {
        $sCaptchaQuestion = false;
        if ($this->NeedCaptcha()) {
            $num1 = rand(1, 10);
            $num2 = rand(1, 10);
            $val = $num1 + $num2;
            $_SESSION[self::SESSION_CAPTCHA] = $val;
            $sCaptchaQuestion = ('Was ergibt '.$num1.' + '.$num2.' ?');
        }

        return $sCaptchaQuestion;
    }