Faction Plugin Not Working

I have a bukkit GUI server and I have a few plugins but whenever I try and download factions plugin (from the web/from the GUI) I put factions.jar in my plugins folder but whenever I restart/reload my server the factions folder isn't there and when I do /plugins factions isn't there.

Here is a list of my other plugins:
CustomCommands
CustomItems
DisableMobs
Essentials
EssentialsAntiBuild
EssentialsChat
EssentialsProtect
EssentialsSpawn
GroupManager
InsanityRun
KillAllMobs
LobbyEffects
mcMMO
OpenPlayerInventory
PerWorldPlugins
WorldEdit
WorldGuard
World Portal