@Mariusz Iwaniuk 

Well the person in the post you linked to appears to have the same problem as me.
I also have a valid and activated license...

Weird...

Well I suppose I have to try to reinstall and probably contact support...

@mmcdara

WHY.mw 

Is the problem that it changes the sine function into its complex representation? I don't understand

EDIT: Nope, your version also doesn't work. When I press return again on the function definition line it also gives me the same error