horseslol

17:37:02 [SEVERE] Could not pass event ChunkLoadEvent to NaturalHorses v1.0.5
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:427)
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
        at org.bukkit.craftbukkit.v1_6_R2.chunkio.ChunkIOProvider.callStage2(ChunkIOProvider.java:58)
        at org.bukkit.craftbukkit.v1_6_R2.chunkio.ChunkIOProvider.callStage2(ChunkIOProvider.java:13)
        at org.bukkit.craftbukkit.v1_6_R2.util.AsynchronousExecutor$Task.finish(AsynchronousExecutor.java:179)
        at org.bukkit.craftbukkit.v1_6_R2.util.AsynchronousExecutor.finishActive(AsynchronousExecutor.java:287)
        at org.bukkit.craftbukkit.v1_6_R2.chunkio.ChunkIOExecutor.tick(ChunkIOExecutor.java:30)
        at net.minecraft.server.v1_6_R2.MinecraftServer.t(MinecraftServer.java:529)
        at net.minecraft.server.v1_6_R2.DedicatedServer.t(DedicatedServer.java:226)
        at net.minecraft.server.v1_6_R2.MinecraftServer.s(MinecraftServer.java:486)
        at net.minecraft.server.v1_6_R2.MinecraftServer.run(MinecraftServer.java:419)
        at net.minecraft.server.v1_6_R2.ThreadServerApplication.run(SourceFile:582)
Caused by: java.lang.IllegalArgumentException: Cannot spawn an entity for org.bukkit.entity.Horse
        at org.bukkit.craftbukkit.v1_6_R2.CraftWorld.spawn(CraftWorld.java:1022)
        at org.bukkit.craftbukkit.v1_6_R2.CraftWorld.spawn(CraftWorld.java:792)
        at org.bukkit.craftbukkit.v1_6_R2.CraftWorld.spawnEntity(CraftWorld.java:339)
        at au.com.addstar.naturalhorses.ChunkListener.onChunkLoad(ChunkListener.java:98)
        at sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
        ... 13 more