.
You are using a really cheap underpowered hub more than likely, your miners are not getting enough power and not submitting any shares at all.
Get a better USB hub, there's a thread out there listing known good ones. Either that or just buy a dlink dub-h7.
This is the hub I'm using:
http://www.amazon.com/gp/product/B0051PGX2I/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1It has external power.
What about a hub makes it good or not?