I have Yosemite 10.10.2 on my Early 2008 24". Time Machine has been backing up to my WD external hard drives for years. I just purchased a new 2TB My Passport using USB 3.0. It's formatted in Mac OS Extended (Journaled). The device shows up on by desktop and it does store files that I drag into it. However, Time Machine does not recognize it.

Any thoughts? Is it Time Machine or the 3.0 USB?