Activity in the forum is one factor. You have been here for four years (1,530days), and if you look at your profile's statistics tab that only comes to 0.08 posts per day, and as PooMan said you need to build your post count, post count and activity go hand in hand.
Why there is no mention? You would have to ask one of the Mods or Admins for that or ask your question in Custom Made Sig and Avatar 
. If you do, post back here with a link, I'd be interested in that also.