public function updateMessage($id = null, $message = null) {
		if (empty($id) || !$this->exists($id)) {
			return false;
		}

		$message = (string)$message;
		if (empty($message)) {
			$message = null;
		}

		$this->id = (int)$id;

		return (bool)$this->saveField('failure_message', $message);
	}