USB to Ethernet adaptor does not work on Macbook Air

I purchased a macbook air in mid 2013, I have an external monitor (not thunderbolt) that connects through a mini display cable. Unfortunately I also need an ethernet connection while using the external monitor. The out of the box solution currently requires use of a thunderbolt to ethernet adaptor. I am using the thunderbolt port for my external monitor.

I purchased a rocketfish USB to ethernet adapter (model: RF-PCC132) at best buy, installed the driver. The USB to ethernet adaptor appears in network preferences but does not detect the ethernet connection. It always shows "disconnected".

Any help or suggestions? I tried removing it and re-adding it to the network preference configuration but no luck so far.

Running OS 10.8.5

thanks!