mcmmorankup erroe

org.bukkit.command.CommandException: Unhandled exception executing command 'mru' in plugin Mcmmorankup v0.2
	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:42)
	at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:166)
	at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:479)
	at org.bukkit.craftbukkit.entity.CraftPlayer.performCommand(CraftPlayer.java:234)
	at org.zonedabone.commandsigns.CommandSignsClickHandler$RunHandler.run(CommandSignsClickHandler.java:380)
	at org.bukkit.craftbukkit.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:126)
	at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:533)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:459)
	at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)
Caused by: java.lang.NullPointerException
	at me.stutiguias.listeners.CommandListener.onCommand(CommandListener.java:38)
	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:40)