GB error

2012-01-15 10:20:24 [SEVERE] Could not pass event PLAYER_QUIT to VirtualChest
java.lang.NoSuchMethodError: org.bukkit.configuration.MemorySection.isNaturallyStorable(Ljava/lang/Object;)Z
	at com.Balor.Tools.Configuration.ExMemorySection.isNaturallyStorable(ExMemorySection.java:108)
	at com.Balor.Tools.Configuration.File.ExtendedConfiguration.serializeValues(ExtendedConfiguration.java:336)
	at com.Balor.Tools.Configuration.File.ExtendedConfiguration.saveToString(ExtendedConfiguration.java:206)
	at com.Balor.Tools.Configuration.File.ExFileConfiguration.save(ExFileConfiguration.java:66)
	at com.Balor.Tools.Configuration.File.ExtendedConfiguration.save(ExtendedConfiguration.java:124)
	at com.Balor.utils.FilesManager.createWorldFile(FilesManager.java:266)
	at com.Balor.Listeners.GPPlayerListener.onPlayerQuit(GPPlayerListener.java:68)
	at org.bukkit.plugin.java.JavaPluginLoader$2.execute(JavaPluginLoader.java:280)
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:341)
	at net.minecraft.server.ServerConfigurationManager.disconnect(ServerConfigurationManager.java:161)
	at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:660)
	at net.minecraft.server.NetworkManager.b(NetworkManager.java:231)
	at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:100)
	at org.getspout.spout.SpoutNetServerHandler.a(SpoutNetServerHandler.java:587)
	at net.minecraft.server.NetworkListenThread.a(SourceFile:108)
	at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:536)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:434)
	at net.minecraft.server.ThreadServerApplication.run(SourceFile:465)