LRPGM worldguard error

[16:57:51 ERROR]: Could not pass event CreatureSpawnEvent to LorinthsRpgMobs vBE
TA-1.6
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:305) ~[spigot-1.8.3.jar:git-Spigot-2ec6f06-7722428]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.jav
a:62) ~[spigot-1.8.3.jar:git-Spigot-2ec6f06-7722428]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.j
ava:502) [spigot-1.8.3.jar:git-Spigot-2ec6f06-7722428]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.j
ava:487) [spigot-1.8.3.jar:git-Spigot-2ec6f06-7722428]
        at org.bukkit.craftbukkit.v1_8_R2.event.CraftEventFactory.callCreatureSp
awnEvent(CraftEventFactory.java:276) [spigot-1.8.3.jar:git-Spigot-2ec6f06-772242
8]
        at net.minecraft.server.v1_8_R2.World.addEntity(World.java:1015) [spigot
-1.8.3.jar:git-Spigot-2ec6f06-7722428]
        at net.minecraft.server.v1_8_R2.SpawnerCreature.a(SpawnerCreature.java:1
82) [spigot-1.8.3.jar:git-Spigot-2ec6f06-7722428]
        at net.minecraft.server.v1_8_R2.WorldServer.doTick(WorldServer.java:227)
 [spigot-1.8.3.jar:git-Spigot-2ec6f06-7722428]
        at net.minecraft.server.v1_8_R2.MinecraftServer.A(MinecraftServer.java:7
67) [spigot-1.8.3.jar:git-Spigot-2ec6f06-7722428]
        at net.minecraft.server.v1_8_R2.DedicatedServer.A(DedicatedServer.java:3
68) [spigot-1.8.3.jar:git-Spigot-2ec6f06-7722428]
        at net.minecraft.server.v1_8_R2.MinecraftServer.z(MinecraftServer.java:6
51) [spigot-1.8.3.jar:git-Spigot-2ec6f06-7722428]
        at net.minecraft.server.v1_8_R2.MinecraftServer.run(MinecraftServer.java
:554) [spigot-1.8.3.jar:git-Spigot-2ec6f06-7722428]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_11]
Caused by: java.lang.IncompatibleClassChangeError: Found interface com.sk89q.wor
ldguard.protection.ApplicableRegionSet, but class was expected
        at com.MobDifficulty.RegionCheck(MobDifficulty.java:714) ~[?:?]
        at com.MobDifficulty.onEntitySpawn(MobDifficulty.java:1533) ~[?:?]
        at sun.reflect.GeneratedMethodAccessor444.invoke(Unknown Source) ~[?:?]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:43) ~[?:1.8.0_11]
        at java.lang.reflect.Method.invoke(Method.java:483) ~[?:1.8.0_11]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:301) ~[spigot-1.8.3.jar:git-Spigot-2ec6f06-7722428]
        ... 12 more