ScoreboardStats Error

2013-05-02 18:37:02 [SEVERE] Could not pass event EntityDeathEvent to ScoreboardStats v1.0
org.bukkit.event.EventException
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:427)
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
	at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
	at org.bukkit.craftbukkit.v1_5_R3.event.CraftEventFactory.callEntityDeathEvent(CraftEventFactory.java:323)
	at net.minecraft.server.v1_5_R3.EntitySkeleton.dropDeathLoot(EntitySkeleton.java:179)
	at net.minecraft.server.v1_5_R3.EntityLiving.die(EntityLiving.java:893)
	at net.minecraft.server.v1_5_R3.EntitySkeleton.die(EntitySkeleton.java:130)
	at net.minecraft.server.v1_5_R3.EntityLiving.damageEntity(EntityLiving.java:750)
	at net.minecraft.server.v1_5_R3.EntityMonster.damageEntity(EntityMonster.java:39)
	at net.minecraft.server.v1_5_R3.EntityArrow.l_(EntityArrow.java:229)
	at net.minecraft.server.v1_5_R3.World.entityJoinedWorld(World.java:1355)
	at net.minecraft.server.v1_5_R3.WorldServer.entityJoinedWorld(WorldServer.java:614)
	at net.minecraft.server.v1_5_R3.World.playerJoinedWorld(World.java:1336)
	at net.minecraft.server.v1_5_R3.World.tickEntities(World.java:1224)
	at net.minecraft.server.v1_5_R3.WorldServer.tickEntities(WorldServer.java:480)
	at net.minecraft.server.v1_5_R3.MinecraftServer.r(MinecraftServer.java:563)
	at net.minecraft.server.v1_5_R3.DedicatedServer.r(DedicatedServer.java:226)
	at net.minecraft.server.v1_5_R3.MinecraftServer.q(MinecraftServer.java:477)
	at net.minecraft.server.v1_5_R3.MinecraftServer.run(MinecraftServer.java:410)
	at net.minecraft.server.v1_5_R3.ThreadServerApplication.run(SourceFile:573)
Caused by: java.lang.NullPointerException
	at me.games647.scoreboardstats.listener.EntityListener.onMobDeath(EntityListener.java:20)
	at sun.reflect.GeneratedMethodAccessor265.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
	... 20 more