error

[23:44:11] [Server thread/INFO]: [Lifestones] Enabling Lifestones v1.8.2
[23:44:11] [Server thread/ERROR]: Error occurred while enabling Lifestones v1.8.2 (Is it up to date?)
java.lang.IllegalArgumentException: No enum constant org.bukkit.event.EventPriority.Highest
	at java.lang.Enum.valueOf(Enum.java:236) ~[?:1.7.0_60]
	at org.bukkit.event.EventPriority.valueOf(EventPriority.java:6) ~[spigot.jar:git-Spigot-1502]
	at com.cyprias.Lifestones.Lifestones.onEnable(Lifestones.java:126) ~[?:?]
	at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:316) ~[spigot.jar:git-Spigot-1502]
	at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:324) [spigot.jar:git-Spigot-1502]
	at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:405) [spigot.jar:git-Spigot-1502]
	at org.bukkit.craftbukkit.v1_7_R3.CraftServer.loadPlugin(CraftServer.java:465) [spigot.jar:git-Spigot-1502]
	at org.bukkit.craftbukkit.v1_7_R3.CraftServer.enablePlugins(CraftServer.java:383) [spigot.jar:git-Spigot-1502]
	at net.minecraft.server.v1_7_R3.MinecraftServer.n(MinecraftServer.java:359) [spigot.jar:git-Spigot-1502]
	at net.minecraft.server.v1_7_R3.MinecraftServer.g(MinecraftServer.java:333) [spigot.jar:git-Spigot-1502]
	at net.minecraft.server.v1_7_R3.MinecraftServer.a(MinecraftServer.java:289) [spigot.jar:git-Spigot-1502]
	at net.minecraft.server.v1_7_R3.DedicatedServer.init(DedicatedServer.java:193) [spigot.jar:git-Spigot-1502]
	at net.minecraft.server.v1_7_R3.MinecraftServer.run(MinecraftServer.java:457) [spigot.jar:git-Spigot-1502]
	at net.minecraft.server.v1_7_R3.ThreadServerApplication.run(SourceFile:628) [spigot.jar:git-Spigot-1502]