Fixed Group parent command not working properly

Hey there!
For some reason the group parent command does not seem to function for whatever reason.

When i type in the command "group parent staff default"
It basically reports back with the usage syntax, as seen in this picture http://i.imgur.com/txYcgVx.png I've tried to read the Oxide permission guide, but i cant seem to find out what i am doing wrong.

Cheers.