22:06:44 [SCHWERWIEGEND] null
org.bukkit.command.CommandException: Unhandled exception executing command 'mcmmo' in plugin mcMMO v1.0.39
	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:37)
	at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:129)
	at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:320)
	at net.minecraft.server.NetServerHandler.handleCommand(NetServerHandler.java:713)
	at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:677)
	at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:670)
	at net.minecraft.server.Packet3Chat.a(Packet3Chat.java:33)
	at net.minecraft.server.NetworkManager.b(NetworkManager.java:226)
	at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:85)
	at net.minecraft.server.NetworkListenThread.a(SourceFile:105)
	at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:451)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:361)
	at net.minecraft.server.ThreadServerApplication.run(SourceFile:422)
Caused by: java.lang.NoClassDefFoundError: org/bukkitcontrib/player/ContribCraftPlayer
	at com.gmail.nossr50.mcMMO.onCommand(mcMMO.java:632)
	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:35)
	... 12 more