Woking Seagate external HDD not showing up anywhere on my new Macbook Pro.

I can plug this same external into the Macbook that I'm replacing and it works fine. Both are running Yosemite. The HDD is powered externally as well. Disk doesn't show up in Disk Utility either. HDD has a USB 3.0 as well. Can't think of anything else relevant to post here. Ask any questions if you need more info. Help is GREATLY appreciated.