Plugin Help PermissionsEx Not creating a folder

I recently installed pex to my server and when i go in game and do /pex nothing happens. Then when I go into my plugins folder there is no permissionsEx folder. I did read that if there are any other permission plugins there will be problems. These are the plugins I have installed:

AdminFun
ChestShop
Citizens
ClearLag
CommandBook
CraftBukkitUpToDate
dynmap
TimTheEnchanter
Essentials
Factions
FoundBoxx
godPowers
HoloAPI
Jobs
mcMMO
MobDisguise
Multiverse-Core
Multiverse-NetherPortals
Multiverse-SignPortals
NoCheatPlus
NoLagg
OpenInv
PermissionsEx
WorldEdit
WorldGuard

Thanks.