11:56:57 [SEVERE] java.lang.NumberFormatException: For input string: ""
11:56:57 [SEVERE]       at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
11:56:57 [SEVERE]       at java.lang.Integer.parseInt(Integer.java:504)
11:56:57 [SEVERE]       at java.lang.Integer.parseInt(Integer.java:527)
11:56:57 [SEVERE]       at org.mcsg.double0negative.spleef.events.ClickSignEvent.clickHandler(ClickSignEvent.java:44)
11:56:57 [SEVERE]       at sun.reflect.GeneratedMethodAccessor40.invoke(Unknown Source)
11:56:57 [SEVERE]       at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
11:56:57 [SEVERE]       at java.lang.reflect.Method.invoke(Method.java:601)
11:56:57 [SEVERE]       at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:339)
11:56:57 [SEVERE]       at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
11:56:57 [SEVERE]       at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
11:56:57 [SEVERE]       at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
11:56:57 [SEVERE]       at org.bukkit.craftbukkit.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:177)
11:56:57 [SEVERE]       at net.minecraft.server.ItemInWorldManager.interact(ItemInWorldManager.java:371)
11:56:57 [SEVERE]       at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:660)
11:56:57 [SEVERE]       at net.minecraft.server.Packet15Place.handle(SourceFile:58)
11:56:57 [SEVERE]       at net.minecraft.server.NetworkManager.b(NetworkManager.java:290)
11:56:57 [SEVERE]       at net.minecraft.server.NetServerHandler.d(NetServerHandler.java:112)
11:56:57 [SEVERE]       at net.minecraft.server.ServerConnection.b(SourceFile:39)
11:56:57 [SEVERE]       at net.minecraft.server.DedicatedServerConnection.b(SourceFile:30)
11:56:57 [SEVERE]       at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:596)
11:56:57 [SEVERE]       at net.minecraft.server.DedicatedServer.r(DedicatedServer.java:222)
11:56:57 [SEVERE]       at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:494)
11:56:57 [SEVERE]       at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:426)
11:56:57 [SEVERE]       at net.minecraft.server.ThreadServerApplication.run(SourceFile:856)