[NTG-context] bold is not working (simplefonts)

Hello, I want to get bold text - without "simplefonts" it is working - with "simplefonts" it does not work. What is wrong and what do I have to do? My example: \usemodule[simplefonts] \setmainfont[Allerlight] \starttext This is not bold! {\bf Is this bold?} This is not bold! \stoptext Regards Jannis