2013-11-30 10:22:44 [INFO] [Autorank] Enabling Autorank v2.7.1 Beta
2013-11-30 10:22:44 [INFO] [Autorank] Simple config file loaded
2013-11-30 10:22:44 [INFO] [Autorank] Advanced config file loaded
2013-11-30 10:22:44 [INFO] [Autorank] New playerdata.yml file loaded. AR can keep track of player progress now!
2013-11-30 10:22:44 [INFO] [Autorank] Interval check every 5 minutes.
2013-11-30 10:22:44 [INFO] [Autorank] Data file loaded
2013-11-30 10:22:44 [INFO] [Autorank] Essentials was found! AFK integration can be used.
2013-11-30 10:22:44 [INFO] [Autorank] Vault Hooked!
2013-11-30 10:22:44 [INFO] [Autorank] Hooked into Stats! Stats requirements can be used.
2013-11-30 10:22:44 [SEVERE] Error occurred while enabling Autorank v2.7.1 Beta (Is it up to date?)
java.lang.ClassCastException: com.massivecraft.factions.P cannot be cast to com.massivecraft.factions.Factions
at me.armar.plugins.autorank.factionapi.FactionsHandler.setupFactions(FactionsHandler.java:29)
at me.armar.plugins.autorank.Autorank.onEnable(Autorank.java:126)
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:217)
at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:457)
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:382)
at org.bukkit.craftbukkit.v1_6_R3.CraftServer.loadPlugin(CraftServer.java:288)
at org.bukkit.craftbukkit.v1_6_R3.CraftServer.enablePlugins(CraftServer.java:270)
at net.minecraft.server.v1_6_R3.MinecraftServer.l(MinecraftServer.java:331)
at net.minecraft.server.v1_6_R3.MinecraftServer.f(MinecraftServer.java:308)
at net.minecraft.server.v1_6_R3.MinecraftServer.a(MinecraftServer.java:268)
at net.minecraft.server.v1_6_R3.DedicatedServer.init(DedicatedServer.java:165)
at net.minecraft.server.v1_6_R3.MinecraftServer.run(MinecraftServer.java:409)
at net.minecraft.server.v1_6_R3.ThreadServerApplication.run(SourceFile:583)

It seems that there is an error with Factions. I'll look into it.

Temp work around ? i'm still waiting to release my server, as the plugin will be the core of it :)

Try using Factions 2.2.1 and mcore 6.8.1

Factions 2.2.2 and mcore 6.9.1 are supported by Autorank 2.7.2 Beta.