Tutaj jest troche inna metoda, taki trick można powiedzieć, dlatego aktywacja jest troche bardziej skomplikowana niż przy typowych modach odgłosów załogi.
There is chance that the OP have the game installed in various places, the modpack was installed to old location, but version.xml is from new one.
Make sure you are installing to right place, don't let the installer guess it for you, because if you have more clients it will most likely point you to old one.