You must not = Du darfst nicht
Just in case you mixed that up
Du musst nicht = You needn't
BTW There are cracks for versions 2.0.9 (retail I guess since this is the RLD crack) and 2.1.0...
Dunno what version you have, but you can update to 2.0.9 using the link from GCW:
http://www.gameshadowus.com/content/...2.0.9_5280.asp
Or update through the ingame updater and use the 2.1.0 patch
Good luck