My Book Essential (USB3) not recognised on my NEW macbook pro OS10.10.2 (yosemite)

Hi I just bought a new Macbook pro OS X10.10.2 and the “My Book Essential” (USB3) is not mounting. It is not recognised in disk utilities either.

I still have my old Macbook air OS X10.9.5 and it recognises it.
It has been reformated to MAC OS extended (journaled).

I have downloaded from  http://support.wdc.com/product/download.asp?groupid=125&lang=en

Tried

on the old mac - to see if it was the firmware 

I have another portable hard drive that the Pro recognises. and it recognises USB sticks, but it wont recognises the WD My Book Essential (1TB)

Thanks for any help

Cath

Hello and welcome to the WD Community.

Make sure that the new computer have all the latest updates installed and when you test the My Book, make sure that the power adapter is connected to the wall outlet.

Hi,

Thanks, yes it has all the latest updates, and it is connected to the wall outlet.