Today i have reached level 27, so i unlocked the scarab and bought it. After a game i wanted to create a new class with scarab but there was written that i need a weapon unlock.i bougt it already and i can also use it, but i cant unlock any attachments or create new classes with scarab.
pls help

This happened with me but with the JAW, you need to save your stuff when you're connected to a server in it's lobby, you're gonna have to get another weapon unlock bonus and unlock it again.