Shutdown PC's via Group Policy - Server 2012 Essentials

Argh!!.... getting really frustrated with this now, hoping someone can point out what i'm doing wrong.

Trying to get all of our computers to shut down at 7PM every night via GPO.

1. Created new GPO
2. Computer configuration > Preferences >> Control Panel settings > Shedule Tasks
3. Run > c:\windows\system32\shutdown.exe
4. Arguments > -f -s
5. Schedule time for shutdown
   
6. Run as administrator
   
7. gpupdate /force on both server and PC, rebooted PC

I think the above is correct but it wont run.

PC's are running windows 8.1 pro if that makes any difference.

Help!!