帮忙看一下是什么问题，本人实在是没有办法了

实体错误
java.lang.NoSuchMethodError: net.minecraft.entity.player.EntityPlayer.func_71011_bu()Lnet/minecraft/item/ItemStack;
        at ckathode.weaponmod.WeaponSpecialDamage.quarterstaffBlock(WeaponSpecialDamage.java:34)
        at ckathode.weaponmod.WeaponSpecialDamage.onLivingHurt(WeaponSpecialDamage.java:23)

这个mod！！！！！