Can you use a portable hardrive with the nexus 7?

[G factor]

So you bought a special micro usb to micro usb cable to connect the N7 to the hub? I have a N7 2nd gen and a powered 3.0 hub. The N7 can't see anything that's plugged into it. I'm rooted, I have Timur's kernel installed and I have StickMount installed.
The N7 is installed in my car and I have a DC/AC converter to power the hub and my external USB DAC converter.
All help and suggestion are MASSIVELY appreciated in advance!!