protected function _createMessage($messageKey, $value)
    {
        if (!isset($this->_messageTemplates[$messageKey])) {
            return null;
        }

        $message = $this->_messageTemplates[$messageKey];

        if (null !== ($translator = $this->getTranslator())) {
            if ($translator->isTranslated($message)) {
                $message = $translator->translate($message);
            } elseif ($translator->isTranslated($messageKey)) {
                $message = $translator->translate($messageKey);
            }
        }

        if ($this->getObscureValue()) {
            $value = str_repeat('*', strlen($value));
        }

        $message = str_replace('%value%', (string) $value, $message);
        foreach ($this->_messageVariables as $ident => $property) {
            $message = str_replace("%$ident%", $this->$property, $message);
        }
        return $message;
    }