Doesn’t seem to be working.

I can’t get this to run. My Late 2009 iMac does not support Power Nap, so I set the wake times on 15 minutes either side of the backup time I requested in the Backup Scheduler for Time Machine app. Like the user below, I am also using a Western Digital external harddrive for my backups.
I am running the latest Yosemite. Hopefully there is a fix after I paid for the app.

MidshipExpress about Backup Scheduler: Time Editor, v1.5.1