error

[14:50:52 ERROR]: Could not pass event InventoryClickEvent to LobbyWatch v1.2
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:310) ~[spigot.jar:git-Spigot-a9631d2-67b2424]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.jav
a:62) ~[spigot.jar:git-Spigot-a9631d2-67b2424]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.j
ava:502) [spigot.jar:git-Spigot-a9631d2-67b2424]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.j
ava:487) [spigot.jar:git-Spigot-a9631d2-67b2424]
        at net.minecraft.server.v1_10_R1.PlayerConnection.a(PlayerConnection.jav
a:1854) [spigot.jar:git-Spigot-a9631d2-67b2424]
        at net.minecraft.server.v1_10_R1.PacketPlayInWindowClick.a(SourceFile:33
) [spigot.jar:git-Spigot-a9631d2-67b2424]
        at net.minecraft.server.v1_10_R1.PacketPlayInWindowClick.a(SourceFile:10
) [spigot.jar:git-Spigot-a9631d2-67b2424]
        at net.minecraft.server.v1_10_R1.PlayerConnectionUtils$1.run(SourceFile:
13) [spigot.jar:git-Spigot-a9631d2-67b2424]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [
?:1.8.0_91]
        at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_91]
        at net.minecraft.server.v1_10_R1.SystemUtils.a(SourceFile:45) [spigot.ja
r:git-Spigot-a9631d2-67b2424]
        at net.minecraft.server.v1_10_R1.MinecraftServer.D(MinecraftServer.java:
737) [spigot.jar:git-Spigot-a9631d2-67b2424]
        at net.minecraft.server.v1_10_R1.DedicatedServer.D(DedicatedServer.java:
399) [spigot.jar:git-Spigot-a9631d2-67b2424]
        at net.minecraft.server.v1_10_R1.MinecraftServer.C(MinecraftServer.java:
673) [spigot.jar:git-Spigot-a9631d2-67b2424]
        at net.minecraft.server.v1_10_R1.MinecraftServer.run(MinecraftServer.jav
a:572) [spigot.jar:git-Spigot-a9631d2-67b2424]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_91]
Caused by: java.lang.NoSuchFieldError: LEVEL_UP
        at com.deathlyflags.LobbyWatch.LobbyWatchCommand.onClickOnItem(LobbyWatc
hCommand.java:183) ~[?:?]
        at sun.reflect.GeneratedMethodAccessor6.invoke(Unknown Source) ~[?:?]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1
.8.0_91]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_91]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:306) ~[spigot.jar:git-Spigot-a9631d2-67b2424]
        ... 15 more
>