[SEVERE] Could not pass event SignChangeEvent to BuyLand v0.5.5
org.bukkit.event.EventException
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:427)
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
	at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
	at net.minecraft.server.v1_4_6.PlayerConnection.a(PlayerConnection.java:1407)
	at net.minecraft.server.v1_4_6.Packet130UpdateSign.handle(SourceFile:46)
	at net.minecraft.server.v1_4_6.NetworkManager.b(NetworkManager.java:290)
	at net.minecraft.server.v1_4_6.PlayerConnection.d(PlayerConnection.java:112)
	at net.minecraft.server.v1_4_6.ServerConnection.b(SourceFile:39)
	at net.minecraft.server.v1_4_6.DedicatedServerConnection.b(SourceFile:30)
	at net.minecraft.server.v1_4_6.MinecraftServer.r(MinecraftServer.java:585)
	at net.minecraft.server.v1_4_6.DedicatedServer.r(DedicatedServer.java:224)
	at net.minecraft.server.v1_4_6.MinecraftServer.q(MinecraftServer.java:481)
	at net.minecraft.server.v1_4_6.MinecraftServer.run(MinecraftServer.java:416)
	at net.minecraft.server.v1_4_6.ThreadServerApplication.run(SourceFile:849)
Caused by: java.lang.ClassCastException: org.bukkit.craftbukkit.v1_4_6.block.CraftBlockState cannot be cast to org.bukkit.block.Sign
	at me.buyland.buyland.ServerChatPlayerListener.onSignChange(ServerChatPlayerListener.java:70)
	at sun.reflect.GeneratedMethodAccessor526.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:601)
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
	... 14 more