Pwteaks Error

2013-03-21 07:11:56 [SEVERE] Error occurred while enabling PTweaks v6.0.2 (Is it up to date?)
java.lang.NoClassDefFoundError: org/bukkit/craftbukkit/v1_5_R1/CraftServer
	at me.devplugin.ptweaks.AutoSaveStopper.<init>(AutoSaveStopper.java:15)
	at me.devplugin.ptweaks.PerformanceTweaks.onEnable(PerformanceTweaks.java:22)
	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_R2.CraftServer.loadPlugin(CraftServer.java:282)
	at org.bukkit.craftbukkit.v1_5_R2.CraftServer.enablePlugins(CraftServer.java:264)
	at net.minecraft.server.v1_5_R2.MinecraftServer.j(MinecraftServer.java:303)
	at net.minecraft.server.v1_5_R2.MinecraftServer.e(MinecraftServer.java:282)
	at net.minecraft.server.v1_5_R2.MinecraftServer.a(MinecraftServer.java:242)
	at net.minecraft.server.v1_5_R2.DedicatedServer.init(DedicatedServer.java:150)
	at net.minecraft.server.v1_5_R2.MinecraftServer.run(MinecraftServer.java:381)
	at net.minecraft.server.v1_5_R2.ThreadServerApplication.run(SourceFile:573)
Caused by: java.lang.ClassNotFoundException: org.bukkit.craftbukkit.v1_5_R1.CraftServer
	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)
	... 13 more