Bukkit

What steps will reproduce the problem?
1. Using /md anymobtype
2. Using /md p playername
3.

What is the expected output? What do you see instead?
Its supposed to disguise you as a mob or another player, instead it returns an internal server message

What version of the product are you using?
v1.81

Do you have an error log of what happened?
2012-08-18 00:47:53 [WARNING] Task of 'MobDisguise' generated an exception
java.lang.NoSuchMethodError: net.minecraft.server.Packet29DestroyEntity.<init>(I)V
    at me.desmin88.mobdisguise.utils.PacketUtils.disguisep2pToAll(PacketUtils.java:76)
    at me.desmin88.mobdisguise.utils.DisguiseTask.run(DisguiseTask.java:23)
    at org.bukkit.craftbukkit.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:126)
    at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:512)
    at net.minecraft.server.DedicatedServer.q(DedicatedServer.java:212)
    at net.minecraft.server.MinecraftServer.p(MinecraftServer.java:476)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:408)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:539)
2012-08-18 00:47:53 [WARNING] Task of 'MobDisguise' generated an exception
java.lang.NoSuchMethodError: net.minecraft.server.Packet29DestroyEntity.<init>(I)V
    at me.desmin88.mobdisguise.utils.PacketUtils.disguisep2pToAll(PacketUtils.java:76)
    at me.desmin88.mobdisguise.utils.DisguiseTask.run(DisguiseTask.java:23)
    at org.bukkit.craftbukkit.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:126)
    at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:512)
    at net.minecraft.server.DedicatedServer.q(DedicatedServer.java:212)
    at net.minecraft.server.MinecraftServer.p(MinecraftServer.java:476)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:408)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:539)

Please provide any additional information below.

These are the plugins we use: GroupManager, WorldEdit, NoVoidDamage, mmSupernaturals, Permissions, mcbans, Vault, Votifier, mcMMO, MobDisguise, WorldGuard, MoneyDrop, Essentials, Jobs, EssentialsXMPP, EssentialsProtect, EssentialsSpawn, HawkEye, EssentialsGeoIP, Sign Bank, EssentialsChat, Factions

This is the version of Java we run java version "1.7.0_05-icedtea"

Our operating System is unix CentOS 6

Our creaftbukkit installation is 1.3.1 R1.0

ye i am getting that error too is there any way to fix it?