Hey guys, since this is cropping up as a common AC problem, I thought I would address it. It's in regards to the 3 threads with at least 3 comments option.
You can have 6 threads of at least 3 comments from you and that would work, but you can't only have 3 threads of less than 10 comments from you to pass AC.
.... So I'm playing Professor Layton at the moment and seriously thought this was worded exactly like some puzzle hints. I'M REALLY BAD AT THE MATH ONES, DANDY