SignShop console error log

[23:42:39 ERROR]: Could not pass event SSCreatedEvent to SignShop v2.9.1Dev
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:305) ~[spigot.jar:git-Spigot-a926b96-313bc52]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot.jar:git-Spigot-a926b96-313bc52]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigot.jar:git-Spigot-a926b96-313bc52]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigot.jar:git-Spigot-a926b96-313bc52]
        at org.wargamer2010.signshop.SignShop.scheduleEvent(SignShop.java:194) [SignShop.jar:?]
        at org.wargamer2010.signshop.listeners.SignShopPlayerListener.onPlayerInteract(SignShopPlayerListener.java:200) [SignShop.jar:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0_72]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[?:1.7.0_72]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.7.0_72]
        at java.lang.reflect.Method.invoke(Method.java:606) ~[?:1.7.0_72]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:301) [spigot.jar:git-Spigot-a926b96-313bc52]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) [spigot.jar:git-Spigot-a926b96-313bc52]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigot.jar:git-Spigot-a926b96-313bc52]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigot.jar:git-Spigot-a926b96-313bc52]
        at org.bukkit.craftbukkit.v1_8_R1.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:226) [spigot.jar:git-Spigot-a926b96-313bc52]
        at org.bukkit.craftbukkit.v1_8_R1.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:193) [spigot.jar:git-Spigot-a926b96-313bc52]
        at net.minecraft.server.v1_8_R1.PlayerInteractManager.a(PlayerInteractManager.java:107) [spigot.jar:git-Spigot-a926b96-313bc52]
        at net.minecraft.server.v1_8_R1.PlayerConnection.a(PlayerConnection.java:588) [spigot.jar:git-Spigot-a926b96-313bc52]
        at net.minecraft.server.v1_8_R1.PacketPlayInBlockDig.a(SourceFile:40) [spigot.jar:git-Spigot-a926b96-313bc52]
        at net.minecraft.server.v1_8_R1.PacketPlayInBlockDig.a(SourceFile:10) [spigot.jar:git-Spigot-a926b96-313bc52]
        at net.minecraft.server.v1_8_R1.PacketHandleTask.run(SourceFile:13) [spigot.jar:git-Spigot-a926b96-313bc52]
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) [?:1.7.0_72]
        at java.util.concurrent.FutureTask.run(FutureTask.java:262) [?:1.7.0_72]
        at net.minecraft.server.v1_8_R1.MinecraftServer.z(MinecraftServer.java:683) [spigot.jar:git-Spigot-a926b96-313bc52]
        at net.minecraft.server.v1_8_R1.DedicatedServer.z(DedicatedServer.java:316) [spigot.jar:git-Spigot-a926b96-313bc52]
        at net.minecraft.server.v1_8_R1.MinecraftServer.y(MinecraftServer.java:623) [spigot.jar:git-Spigot-a926b96-313bc52]
        at net.minecraft.server.v1_8_R1.MinecraftServer.run(MinecraftServer.java:526) [spigot.jar:git-Spigot-a926b96-313bc52]
        at java.lang.Thread.run(Thread.java:745) [?:1.7.0_72]
Caused by: java.lang.IncompatibleClassChangeError: Found interface com.sk89q.worldguard.protection.ApplicableRegionSet, but class was expected
        at org.wargamer2010.signshop.listeners.sslisteners.WorldGuardChecker.onSSBuildEvent(WorldGuardChecker.java:28) ~[?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0_72]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[?:1.7.0_72]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.7.0_72]
        at java.lang.reflect.Method.invoke(Method.java:606) ~[?:1.7.0_72]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:301) ~[spigot.jar:git-Spigot-a926b96-313bc52]
        ... 27 more