ok checked the stats code...there's a rule to not count sets which only consist of biosroms (and are not biossets)....now I only need to remember why
it's because of this fix:
3.125a
* fixed: wrong sets statistic count for sets which only consists of nodump rom + chds + bios roms
hmm....looks like some weird exception...will check what can be done....
ok...fixed for next version