Citizens Error

13:45:50 [SEVERE] null
org.bukkit.command.CommandException: Unhandled exception executing command 'npc' in plugin Citizens v1.07
	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:37)
	at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:85)
	at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:255)
	at net.minecraft.server.NetServerHandler.handleCommand(NetServerHandler.java:677)
	at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:640)
	at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:634)
	at net.minecraft.server.Packet3Chat.a(Packet3Chat.java:32)
	at net.minecraft.server.NetworkManager.a(NetworkManager.java:195)
	at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:74)
	at net.minecraft.server.NetworkListenThread.a(SourceFile:100)
	at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:370)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:285)
	at net.minecraft.server.ThreadServerApplication.run(SourceFile:394)
Caused by: java.lang.NullPointerException
	at com.fullwall.Citizens.Economy.ItemInterface.hasEnough(ItemInterface.java:25)
	at com.fullwall.Citizens.Economy.EconomyHandler.canBuy(EconomyHandler.java:38)
	at com.fullwall.Citizens.CommandExecutors.BasicExecutor.onCommand(BasicExecutor.java:48)
	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:35)
	... 12 more