prisonpearl

2013-03-19 15:57:51 [INFO] [PrisonPearl] Enabling PrisonPearl v1.5.7
2013-03-19 15:57:51 [INFO] prisonpearls.txt not exist, creating.
2013-03-19 15:57:51 [SEVERE] Error occurred while enabling PrisonPearl v1.5.7 (Is it up to date?)
java.lang.NoClassDefFoundError: net/minecraft/server/v1_4_R1/World
	at com.untamedears.PrisonPearl.PrisonPearlPlugin.onEnable(PrisonPearlPlugin.java:82)
	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.v1_5_R1.CraftServer.loadPlugin(CraftServer.java:282)
	at org.bukkit.craftbukkit.v1_5_R1.CraftServer.enablePlugins(CraftServer.java:264)
	at net.minecraft.server.v1_5_R1.MinecraftServer.j(MinecraftServer.java:303)
	at net.minecraft.server.v1_5_R1.MinecraftServer.e(MinecraftServer.java:282)
	at net.minecraft.server.v1_5_R1.MinecraftServer.a(MinecraftServer.java:242)
	at net.minecraft.server.v1_5_R1.DedicatedServer.init(DedicatedServer.java:150)
	at net.minecraft.server.v1_5_R1.MinecraftServer.run(MinecraftServer.java:381)
	at net.minecraft.server.v1_5_R1.ThreadServerApplication.run(SourceFile:573)
Caused by: java.lang.ClassNotFoundException: net.minecraft.server.v1_4_R1.World
	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(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	... 12 more