Error "Could not pass event WorldInitEvent"

[inode64]

In my craftbukkit 1.4.6-r0.1 to 1.4.6-r3 show this error:

2013-01-03 22:02:00 [SEVERE] Could not pass event WorldInitEvent to AlmostFlatLands v0.1
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.CraftServer.createWorld(CraftServer.java:725)
at org.bukkit.Bukkit.createWorld(Bukkit.java:156)
at org.bukkit.WorldCreator.createWorld(WorldCreator.java:235)
at com.onarandombox.MultiverseCore.utils.WorldManager.addWorld(WorldManager.java:137)
at com.onarandombox.MultiverseCore.utils.WorldManager.addWorld(WorldManager.java:91)
at com.onarandombox.MultiverseCore.utils.WorldManager.loadWorlds(WorldManager.java:557)
at com.onarandombox.MultiverseCore.MultiverseCore.onEnable(MultiverseCore.java:242)
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:217)
at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:457)
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:381)
at org.bukkit.craftbukkit.CraftServer.loadPlugin(CraftServer.java:282)
at org.bukkit.craftbukkit.CraftServer.enablePlugins(CraftServer.java:264)
at net.minecraft.server.MinecraftServer.j(MinecraftServer.java:321)
at net.minecraft.server.MinecraftServer.e(MinecraftServer.java:300)
at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:259)
at net.minecraft.server.DedicatedServer.init(DedicatedServer.java:149)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:399)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:849)
Caused by: java.lang.NoClassDefFoundError: org/bukkit/craftbukkit/v1_4_6/CraftWorld
at uk.co.jacekk.bukkit.almostflatlands.WorldListener.onWorldInit(WorldListener.java:28)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
... 21 more
Caused by: java.lang.ClassNotFoundException: org.bukkit.craftbukkit.v1_4_6.CraftWorld
at org.bukkit.plugin.java.PluginClassLoader.findClass0(PluginClassLoader.java:70)
at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:53)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
... 27 more

[betterphp]

Are you using a modified version of CraftBukkit ?

[inode64]

No , download from git

I use this plugins

-rw-rw-r-- 1 36 35 45011 ene 1 12:03 almostflatlands-0.1-SNAPSHOT.jar
-rw-rw-r-- 1 36 35 465523 oct 28 09:21 CityWorld.jar
-rw-rw-r-- 1 36 35 6156 ene 1 12:12 CleanroomGenerator.jar
-rw-r--r-- 1 36 35 705614 dic 21 00:31 Essentials.jar
-rw-r--r-- 1 36 35 652532 dic 21 00:31 EssentialsProtect.jar
-rw-rw-r-- 1 36 35 14611 ene 1 13:06 GladiatorPlugin_V1.0.jar
-rw-rw-r-- 1 36 35 126018 ene 1 12:38 hothgenerator.jar
-rw-rw-r-- 1 500 500 23081 ene 3 21:17 invtoolkit.jar
-rw-r--r-- 1 36 35 75125 dic 29 09:52 IslandWorld.jar
-rw-rw-r-- 1 500 500 450231 dic 26 13:03 LWC.jar
-rw-rw-r-- 1 36 35 325807 dic 30 11:58 Multiverse-Core-2.4.jar
-rw-rw-r-- 1 36 35 30862 dic 30 14:23 Multiverse-NetherPortals-2.4.jar
-rw-rw-r-- 1 36 35 81462 dic 30 14:22 Multiverse-Portals-2.4.jar
-rw-rw-r-- 1 36 35 24365 dic 30 13:08 Multiverse-SignPortals-2.4.jar
-rw-rw-r-- 1 36 35 29617 dic 25 18:20 PermissionsBukkit-2.0.jar
-rw-rw-r-- 1 36 35 112595 dic 25 18:20 SimpleSpawn.jar
-rw-rw-rwT 1 36 35 763887 dic 29 20:01 WorldEdit.jar
-rw-rw-rwT 1 36 35 322197 dic 29 16:48 WorldGuard.jar

[betterphp]

Can you try the version from dl.bukkit.org instead, org/bukkit/craftbukkit/v1_4_6/CraftWorld should exist.