Bukkit

What steps will reproduce the problem?
1.in game with /md command
2.while attempting to perform this command (only with minecraft 1.3)
3.going here to report here ^^

What version of the product are you using?
1.81 on bukkit 1.3.1

Do you have an error log of what happened?

2012-09-13 21:27:55 [WARNING] Task of 'MobDisguise' generated an exception
java.lang.NoSuchFieldError: f
    at me.desmin88.mobdisguise.utils.PacketUtils.packetMaker(PacketUtils.java:146)
    at me.desmin88.mobdisguise.utils.PacketUtils.disguiseToAll(PacketUtils.java:61)
    at me.desmin88.mobdisguise.utils.DisguiseTask.run(DisguiseTask.java:25)
    at org.bukkit.craftbukkit.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:126)
    at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:510)
    at net.minecraft.server.DedicatedServer.q(DedicatedServer.java:212)
    at net.minecraft.server.MinecraftServer.p(MinecraftServer.java:474)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:406)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:539)

HAVING THE EXACT SAME DAM PROBLEM...