Could not pass event PlayerMoveEvent

16:35:37 [SEVERE] Could not pass event PlayerMoveEvent to TheWalls v1.1.0.1
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_5_R3.PlayerConnection.a(PlayerConnection.java:216)
at net.minecraft.server.v1_5_R3.Packet10Flying.handle(SourceFile:136)
at net.minecraft.server.v1_5_R3.NetworkManager.b(NetworkManager.java:292)
at net.minecraft.server.v1_5_R3.PlayerConnection.d(PlayerConnection.java:109)
at net.minecraft.server.v1_5_R3.ServerConnection.b(SourceFile:35)
at net.minecraft.server.v1_5_R3.DedicatedServerConnection.b(SourceFile:30)
at net.minecraft.server.v1_5_R3.MinecraftServer.r(MinecraftServer.java:581)
at net.minecraft.server.v1_5_R3.DedicatedServer.r(DedicatedServer.java:226)
at net.minecraft.server.v1_5_R3.MinecraftServer.q(MinecraftServer.java:477)
at net.minecraft.server.v1_5_R3.MinecraftServer.run(MinecraftServer.java:410)
at net.minecraft.server.v1_5_R3.ThreadServerApplication.run(SourceFile:573)
Caused by: java.lang.NullPointerException
at rubik_cube_man.plugins.walls.PlayerMoveListner.onPlayerMove(PlayerMoveListner.java:23)
at sun.reflect.GeneratedMethodAccessor16.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