Doxygen issue: chapter are all 0

I have some doxygen groups defined in a fake .h file

@defgroup MainGroup@brief ...@defgroup SubGroup1@brief ...@ingroup MainGroup@defgroup SubGroup1@brief ...@ingroup MainGroup

now the problem is that when generating the latex pdf, all chapters are starting with 0:

MainGroup0.1SubGroup10.2SubGroup20.3

and all the pdf is a huge chapter 0.

To fix this I always need to tweak the refman.tex files by hand by inserting \chapter instead of \section, any way to have doxygen generate a proper index?