HELP PLEASE!!!

Hi, I am having trouble using a plugin in my server, you'll see down below
PLEASE help i dont know what to do!



14:01:11 [INFO] Josephman569 issued server command: /NPC
14:01:11 [SEVERE] java.lang.NullPointerException
14:01:11 [SEVERE] at net.citizensnpcs.Citizens.onCommand(Citizens.java:134)
14:01:11 [SEVERE] at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
14:01:11 [SEVERE] at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:186)
14:01:11 [SEVERE] at org.bukkit.craftbukkit.v1_4_R1.CraftServer.dispatchCommand(CraftServer.java:514)
14:01:11 [SEVERE] at net.minecraft.server.v1_4_R1.PlayerConnection.handleCommand(PlayerConnection.java:980)
14:01:11 [SEVERE] at net.minecraft.server.v1_4_R1.PlayerConnection.chat(PlayerConnection.java:898)
14:01:11 [SEVERE] at net.minecraft.server.v1_4_R1.PlayerConnection.a(PlayerConnection.java:853)
14:01:11 [SEVERE] at net.minecraft.server.v1_4_R1.Packet3Chat.handle(Packet3Chat.java:44)
14:01:11 [SEVERE] at net.minecraft.server.v1_4_R1.NetworkManager.b(NetworkManager.java:290)
14:01:11 [SEVERE] at net.minecraft.server.v1_4_R1.PlayerConnection.d(PlayerConnection.java:113)
14:01:11 [SEVERE] at net.minecraft.server.v1_4_R1.ServerConnection.b(SourceFile:39)
14:01:11 [SEVERE] at net.minecraft.server.v1_4_R1.DedicatedServerConnection.b(SourceFile:30)
14:01:11 [SEVERE] at net.minecraft.server.v1_4_R1.MinecraftServer.r(MinecraftServer.java:598)
14:01:11 [SEVERE] at net.minecraft.server.v1_4_R1.DedicatedServer.r(DedicatedServer.java:224)
14:01:11 [SEVERE] at net.minecraft.server.v1_4_R1.MinecraftServer.q(MinecraftServer.java:494)
14:01:11 [SEVERE] at net.minecraft.server.v1_4_R1.MinecraftServer.run(MinecraftServer.java:427)
14:01:11 [SEVERE] at net.minecraft.server.v1_4_R1.ThreadServerApplication.run(SourceFile:849)