Well, I'd say that you don't have enough hubs. I'm creeping up on 300 hubs - sure there are some that aren't much good at all, and get very poor traffic - but I'm fond of some of those hubs, and refuse to delete them.
I either make payout or get really close every month here lately.....but I'm certain that that is because I've got lots more hubs, and some of them have proved pretty steady traffic generators.
Also, in a lot of cases your hubs have to be six months or so old in order for Google to even much like them.
I don't mean to be discouraging - but this article marketing game is hard work, and the game sometimes changes on us as well.