Minecart error

2014-01-30 17:47:21 [SEVERE] Could not pass event VehicleUpdateEvent to MinecartMania v2.1.3
org.bukkit.event.EventException
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:351)
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
	at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredListener.java:31)
	at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:479)
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:464)
	at net.minecraft.entity.item.EntityMinecart.func_70071_h_(EntityMinecart.java:462)
	at net.minecraft.world.World.func_72866_a(World.java:2528)
	at net.minecraft.world.WorldServer.func_72866_a(WorldServer.java:941)
	at net.minecraft.world.World.func_72870_g(World.java:2481)
	at net.minecraft.world.World.func_72939_s(World.java:2293)
	at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:806)
	at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:838)
	at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:320)
	at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:732)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:614)
	at net.minecraft.server.ThreadMinecraftServer.run(SourceFile:573)
Caused by: java.lang.NoClassDefFoundError: Could not initialize class com.afforess.minecartmania.minecarts.MMEntityMinecartChest
	at com.afforess.minecartmania.minecarts.MMMinecart.replaceCart(MMMinecart.java:1062)
	at com.afforess.minecartmania.minecarts.MMMinecart.<init>(MMMinecart.java:97)
	at com.afforess.minecartmania.minecarts.MMStorageCart.<init>(MMStorageCart.java:63)
	at com.afforess.minecartmania.entity.MinecartManiaWorld.getOrCreateMMMinecart(MinecartManiaWorld.java:83)
	at com.afforess.minecartmania.listeners.CoreListener.onVehicleUpdate(CoreListener.java:41)
	at sun.reflect.GeneratedMethodAccessor19.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:349)
	... 15 more