vpac error

2013-09-22 09:32:31 [SEVERE] [VirtualPack] COULD NOT LOAD USER DATA!
2013-09-22 09:32:31 [SEVERE] java.lang.NoClassDefFoundError: net/minecraft/server/v1_6_R2/IInventory
2013-09-22 09:32:31 [SEVERE]    at java.lang.ClassLoader.defineClass1(Native Method)
2013-09-22 09:32:31 [SEVERE]    at java.lang.ClassLoader.defineClass(Unknown Source)
2013-09-22 09:32:31 [SEVERE]    at java.security.SecureClassLoader.defineClass(Unknown Source)
2013-09-22 09:32:31 [SEVERE]    at java.net.URLClassLoader.defineClass(Unknown Source)
2013-09-22 09:32:31 [SEVERE]    at java.net.URLClassLoader.access$100(Unknown Source)
2013-09-22 09:32:31 [SEVERE]    at java.net.URLClassLoader$1.run(Unknown Source)
2013-09-22 09:32:31 [SEVERE]    at java.net.URLClassLoader$1.run(Unknown Source)
2013-09-22 09:32:31 [SEVERE]    at java.security.AccessController.doPrivileged(Native Method)
2013-09-22 09:32:31 [SEVERE]    at java.net.URLClassLoader.findClass(Unknown Source)
2013-09-22 09:32:31 [SEVERE]    at org.bukkit.plugin.java.PluginClassLoader.findClass0(PluginClassLoader.java:80)
2013-09-22 09:32:31 [SEVERE]    at org.bukkit.plugin.java.JavaPluginLoader.getClassByName0(JavaPluginLoader.java:300)
2013-09-22 09:32:31 [SEVERE]    at org.bukkit.plugin.java.PluginClassLoader.findClass0(PluginClassLoader.java:76)
2013-09-22 09:32:31 [SEVERE]    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:53)
2013-09-22 09:32:31 [SEVERE]    at java.lang.ClassLoader.loadClass(Unknown Source)
2013-09-22 09:32:31 [SEVERE]    at java.lang.ClassLoader.loadClass(Unknown Source)
2013-09-22 09:32:31 [SEVERE]    at net.drgnome.virtualpack.VPack.<init>(VPack.java:90)
2013-09-22 09:32:31 [SEVERE]    at net.drgnome.virtualpack.VPlugin.load(VPlugin.java:584)
2013-09-22 09:32:31 [SEVERE]    at net.drgnome.virtualpack.VPlugin.loadFlatfile(VPlugin.java:564)
2013-09-22 09:32:31 [SEVERE]    at net.drgnome.virtualpack.VPlugin.loadUserData0(VPlugin.java:481)
2013-09-22 09:32:31 [SEVERE]    at net.drgnome.virtualpack.VPlugin.loadUserData(VPlugin.java:445)
2013-09-22 09:32:31 [SEVERE]    at net.drgnome.virtualpack.VPlugin.init(VPlugin.java:127)
2013-09-22 09:32:31 [SEVERE]    at net.drgnome.virtualpack.VPlugin.onEnable(VPlugin.java:237)
2013-09-22 09:32:31 [SEVERE]    at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:217)
2013-09-22 09:32:31 [SEVERE]    at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:457)
2013-09-22 09:32:31 [SEVERE]    at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:382)
2013-09-22 09:32:31 [SEVERE]    at org.bukkit.craftbukkit.v1_6_R3.CraftServer.loadPlugin(CraftServer.java:286)
2013-09-22 09:32:31 [SEVERE]    at org.bukkit.craftbukkit.v1_6_R3.CraftServer.enablePlugins(CraftServer.java:268)
2013-09-22 09:32:31 [SEVERE]    at net.minecraft.server.v1_6_R3.MinecraftServer.l(MinecraftServer.java:321)
2013-09-22 09:32:31 [SEVERE]    at net.minecraft.server.v1_6_R3.MinecraftServer.f(MinecraftServer.java:298)
2013-09-22 09:32:31 [SEVERE]    at net.minecraft.server.v1_6_R3.MinecraftServer.a(MinecraftServer.java:258)
2013-09-22 09:32:31 [SEVERE]    at net.minecraft.server.v1_6_R3.DedicatedServer.init(DedicatedServer.java:165)
2013-09-22 09:32:31 [SEVERE]    at net.minecraft.server.v1_6_R3.MinecraftServer.run(MinecraftServer.java:399)
2013-09-22 09:32:31 [SEVERE]    at net.minecraft.server.v1_6_R3.ThreadServerApplication.run(SourceFile:583)
2013-09-22 09:32:31 [SEVERE] Caused by: java.lang.ClassNotFoundException: net.minecraft.server.v1_6_R2.IInventory
2013-09-22 09:32:31 [SEVERE]    at org.bukkit.plugin.java.PluginClassLoader.findClass0(PluginClassLoader.java:70)
2013-09-22 09:32:31 [SEVERE]    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:53)
2013-09-22 09:32:31 [SEVERE]    at java.lang.ClassLoader.loadClass(Unknown Source)
2013-09-22 09:32:31 [SEVERE]    at java.lang.ClassLoader.loadClass(Unknown Source)
2013-09-22 09:32:31 [SEVERE]    ... 33 more
2013-09-22 09:32:31 [INFO] VirtualPack 2.5.6 enabled