Install Thunderbolt Duo on Macbook Pro

My Macbook Pro (2011 running Lion) isnt recognising the My Book Thunderbolt Duo? 

I plug it in and the light comes on on the case, but the laptop just isnt finding it…

I downloaded the WD Drive Utilities to see if that would make a difference but obviously that isnt finding it either.

Im probably missing something really obvious here, but its driving me crazy. 

Anyone able to help?


have you try a different device on that port? you might need to do that to eliminate posibilities.