Error

21:47:20 [SEVERE] null
org.bukkit.command.CommandException: Unhandled exception executing command 'ctf'
 in plugin CaptureTheFlag v0.1
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46)
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:18
6)
        at org.bukkit.craftbukkit.v1_4_6.CraftServer.dispatchCommand(CraftServer
.java:510)
        at net.minecraft.server.v1_4_6.PlayerConnection.handleCommand(PlayerConn
ection.java:980)
        at net.minecraft.server.v1_4_6.PlayerConnection.chat(PlayerConnection.ja
va:898)
        at net.minecraft.server.v1_4_6.PlayerConnection.a(PlayerConnection.java:
853)
        at net.minecraft.server.v1_4_6.Packet3Chat.handle(Packet3Chat.java:44)
        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:59
8)
        at net.minecraft.server.v1_4_6.DedicatedServer.r(DedicatedServer.java:22
4)
        at net.minecraft.server.v1_4_6.MinecraftServer.q(MinecraftServer.java:49
4)
        at net.minecraft.server.v1_4_6.MinecraftServer.run(MinecraftServer.java:
427)
        at net.minecraft.server.v1_4_6.ThreadServerApplication.run(SourceFile:84
9)
Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to org.
bukkit.World
        at com.hotmail.MineCrypt.CTF.CTFCommandExecutor.onCommand(CTFCommandExec
utor.java:68)
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
        ... 15 more
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