Minecraft Bukkit Permissions EX

So I have a question. I'm trying to get my permissions setup for my MC server… But I want to deny or allow people to change their gamemode without being opped. So I did this.

- -essentials.gamemode (To Deny)

But It works no mater what, even if the person is not opped. I'm really confused. I've checked it in a yaml parser and everything looks good…

Added (1). I did put - '*' in the permission but that's just because I don't want to type out every permission myself…

Minecraft is a knock off of starwars