cameraobscura error

2012-12-19 13:54:37 [SEVERE] Could not pass event PlayerInteractEvent to CameraObscura v0.1.0
org.bukkit.event.EventException
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:341)
	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 org.bukkit.craftbukkit.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:177)
	at net.minecraft.server.ItemInWorldManager.interact(ItemInWorldManager.java:376)
	at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:662)
	at net.minecraft.server.Packet15Place.handle(SourceFile:58)
	at net.minecraft.server.NetworkManager.b(NetworkManager.java:290)
	at net.minecraft.server.NetServerHandler.d(NetServerHandler.java:113)
	at net.minecraft.server.ServerConnection.b(SourceFile:39)
	at net.minecraft.server.DedicatedServerConnection.b(SourceFile:30)
	at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:595)
	at net.minecraft.server.DedicatedServer.r(DedicatedServer.java:222)
	at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:493)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:426)
	at net.minecraft.server.ThreadServerApplication.run(SourceFile:856)
Caused by: java.lang.NullPointerException
	at fromgate.obscura.COAlbum.getOwnerCount(COAlbum.java:542)
	at fromgate.obscura.COAlbum.isLimitOver(COAlbum.java:529)
	at fromgate.obscura.COAlbum.developAnyImage(COAlbum.java:255)
	at fromgate.obscura.COAlbum.developTopHalfPhoto(COAlbum.java:346)
	at fromgate.obscura.COAlbum.developTopHalfPhoto(COAlbum.java:339)
	at fromgate.obscura.COListener.onObscuraShot(COListener.java:174)
	at sun.reflect.GeneratedMethodAccessor95.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:339)
	... 16 more