if the hubs powered, it will most likely output the power to the outgoing ports, not the "host" port. you either have to solder or use a Y-cable where 2 sides connect the host-port of the hub and the 770 and the third goes into an outgoing port of the hub, thus getting power out of it.

if you want to use the 770 via usb w/ your pc, you have to temp. disable host mode.
goto xterm, gain root access then enter

echo peripheral > /sys/devices/platform/tahvo-usb/otg_mode