Oxide.grant command doesn't existNot An Issue

I just started my server after adding a plugin that needs oxide.grant permission, but every time i put oxide.grant it says "command doesnt exist"
anyone haves an idea wahts happening?

this is the plugin btw.

https://umod.org/plugins/sign-artist

did you do ownerid first? your server has to know who the one is that's sending the commands ofc :P 
That would mean that Oxide is not installed.
Locked automatically