Installed drive for first time but didn't get message to use time machine

WD External Drives External Drives for Mac
1

Installed drive for first time but didn’t get message to use time machine. Does anyone know why this is happening? I’m using OS X Yosemite. I want it to back up to my time machine.

2

Hi and welcome to the WD community.

When you go to the Time Machine preferences does the drive appear as a backup source? Try to check if the drive is formatted for Mac OS.