item slot machine error 2

Chaositic issued server command: /slot remove SlotMachine1
12:29:26 [SEVERE] null
org.bukkit.command.CommandException: Unhandled exception executing command 'slot
' in plugin ItemSlotMachine v1.2.6
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46)
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:18
9)
        at org.bukkit.craftbukkit.v1_5_R3.CraftServer.dispatchCommand(CraftServe
r.java:523)
        at net.minecraft.server.v1_5_R3.PlayerConnection.handleCommand(PlayerCon
nection.java:971)
        at net.minecraft.server.v1_5_R3.PlayerConnection.chat(PlayerConnection.j
ava:889)
        at net.minecraft.server.v1_5_R3.PlayerConnection.a(PlayerConnection.java
:846)
        at net.minecraft.server.v1_5_R3.Packet3Chat.handle(Packet3Chat.java:44)
        at net.minecraft.server.v1_5_R3.NetworkManager.b(NetworkManager.java:292
)
        at net.minecraft.server.v1_5_R3.PlayerConnection.d(PlayerConnection.java
:115)
        at net.minecraft.server.v1_5_R3.ServerConnection.b(SourceFile:35)
        at net.minecraft.server.v1_5_R3.DedicatedServerConnection.b(SourceFile:3
0)
        at net.minecraft.server.v1_5_R3.MinecraftServer.r(MinecraftServer.java:5
81)
        at net.minecraft.server.v1_5_R3.DedicatedServer.r(DedicatedServer.java:2
26)
        at net.minecraft.server.v1_5_R3.MinecraftServer.q(MinecraftServer.java:4
77)
        at net.minecraft.server.v1_5_R3.MinecraftServer.run(MinecraftServer.java
:410)
        at net.minecraft.server.v1_5_R3.ThreadServerApplication.run(SourceFile:5
73)
Caused by: java.lang.NullPointerException
        at com.DarkBlade12.ItemSlotMachine.SlotMachine.SlotMachine.remove(SlotMa
chine.java:357)
        at com.DarkBlade12.ItemSlotMachine.Commands.ItemSlotMachineCE_slot.onCom
mand(ItemSlotMachineCE_slot.java:115)
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
        ... 15 more