DisguiseCraft ?

21:21:56 [SEVERE] null
org.bukkit.command.CommandException: Unhandled exception executing command 'd' in plugin DisguiseCraft v3.6
	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:42)
	at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:166)
	at forge.bukkit.ForgeCommandMap.dispatch(ForgeCommandMap.java:55)
	at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:497)
	at net.minecraft.server.NetServerHandler.handleCommand(NetServerHandler.java:843)
	at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:799)
	at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:781)
	at net.minecraft.server.Packet3Chat.handle(Packet3Chat.java:34)
	at net.minecraft.server.NetworkManager.b(NetworkManager.java:234)
	at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:119)
	at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:83)
	at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:579)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:467)
	at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)
Caused by: java.lang.NoSuchFieldError: i
	at pgDev.bukkit.DisguiseCraft.Disguise.getMobSpawnPacket(Disguise.java:611)
	at pgDev.bukkit.DisguiseCraft.DisguiseCraft.sendDisguise(DisguiseCraft.java:315)
	at pgDev.bukkit.DisguiseCraft.DisguiseCraft.disguisePlayer(DisguiseCraft.java:216)
	at pgDev.bukkit.DisguiseCraft.listeners.DCCommandListener.onCommand(DCCommandListener.java:1050)
	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:40)
	... 13 more