error

2012-02-11 19:02:00 [SEVERE] Could not pass event org.bukkit.event.block.SignChangeEvent to ChestShop
java.lang.NullPointerException
	at com.Acrobot.ChestShop.Utils.uTowny.isInsideShopPlot(uTowny.java:16)
	at com.Acrobot.ChestShop.Utils.uTowny.canBuild(uTowny.java:29)
	at com.Acrobot.ChestShop.Listeners.signChange.onSignChange(signChange.java:93)
	at org.bukkit.plugin.java.JavaPluginLoader$38.execute(JavaPluginLoader.java:530)
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:57)
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:453)
	at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:1094)
	at net.minecraft.server.Packet130UpdateSign.handle(SourceFile:41)
	at net.minecraft.server.NetworkManager.b(NetworkManager.java:226)
	at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:100)
	at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:78)
	at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:537)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:435)
	at net.minecraft.server.ThreadServerApplication.run(SourceFile:465)
2012-02-11 19:02:02 [INFO] Removing corrupted protection: Private Tabla?f ?2Id=24591 Owner=RoboAdmin Location=[world -723,63,162] Created=2012-02-11 08:49:01.369 Flags= LastAccessed=10 hours 13 minutes 1 second ago
2012-02-11 19:02:03 [INFO] Removing corrupted protection: Private Tabla?f ?2Id=24592 Owner=RoboAdmin Location=[world -723,63,162] Created=2012-02-11 08:49:08.665 Flags= LastAccessed=10 hours 12 minutes 55 seconds ago
2012-02-11 19:02:06 [SEVERE] java.net.SocketException: Socket closed
2012-02-11 19:02:06 [SEVERE] 	at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:99)
2012-02-11 19:02:06 [SEVERE] 	at java.net.SocketOutputStream.write(SocketOutputStream.java:136)
2012-02-11 19:02:06 [SEVERE] 	at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65)
2012-02-11 19:02:06 [SEVERE] 	at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:123)
2012-02-11 19:02:06 [SEVERE] 	at java.io.DataOutputStream.flush(DataOutputStream.java:106)
2012-02-11 19:02:06 [SEVERE] 	at net.minecraft.server.NetworkWriterThread.run(SourceFile:103)