ExtraHardMode Error

12:11 PM [SEVERE] Could not pass event CreatureSpawnEvent to ExtraHardMode v3.5.1
Caused by: java.lang.IncompatibleClassChangeError: Found interface com.sk89q.worldguard.protection.ApplicableRegionSet, but class was expected
	at com.extrahardmode.compatibility.CompatWorldGuard.denySpawn(CompatWorldGuard.java:34)
	at com.extrahardmode.compatibility.CompatHandler.canMonsterSpawn(CompatHandler.java:47)
	at com.extrahardmode.module.EntityHelper.spawn(EntityHelper.java:262)
	at com.extrahardmode.module.EntityHelper.spawnRandomMob(EntityHelper.java:292)
	at com.extrahardmode.features.monsters.MonsterRules.onEntitySpawn(MonsterRules.java:98)
	at sun.reflect.GeneratedMethodAccessor418.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:328)
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
	at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredListener.java:47)
	at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502)
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487)
	at org.bukkit.craftbukkit.v1_7_R4.event.CraftEventFactory.callCreatureSpawnEvent(CraftEventFactory.java:272)
	at net.minecraft.world.World.addEntity(World.java:1737)
	at net.minecraft.world.SpawnerAnimals.func_77192_a(SpawnerAnimals.java:212)
	at net.minecraft.world.WorldServer.func_72835_b(WorldServer.java:247)
	at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:916)
	at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:422)
	at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:803)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:663)
	at java.lang.Thread.run(Unknown Source)