When my custom villager dies it turns into a regular zombie instead of turning into a zombie villager.

 

My custom villager class.

package orangeVillager61.MoDrops.villager;

import net.minecraft.entity.passive.EntityVillager;
import net.minecraft.entity.passive.EntityVillager.EmeraldForItems;
import net.minecraft.entity.passive.EntityVillager.ListItemForEmeralds;
import net.minecraft.entity.passive.EntityVillager.PriceInfo;
import net.minecraft.init.Blocks;
import net.minecraft.init.Items;
import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;
import net.minecraftforge.event.entity.EntityEvent;
import net.minecraftforge.fml.common.event.FMLInitializationEvent;
import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
import net.minecraftforge.fml.common.registry.VillagerRegistry;
import net.minecraftforge.fml.common.registry.VillagerRegistry.VillagerCareer;
import net.minecraftforge.fml.common.registry.VillagerRegistry.VillagerProfession;
import orangeVillager61.MoDrops.Config;
import orangeVillager61.MoDrops.items.MoDropsItems;


public class BioMaker{

public static final boolean enableSaltTrader = Config.enableCustomVillagers;
public static ItemStack Charcoal = new ItemStack (Items.COAL, 1, 1);
protected static final VillagerRegistry.VillagerProfession PROFESSION = new VillagerRegistry.VillagerProfession("md:BioMaker", "minecraft:textures/entity/villager/villager.png", "md:textures/entity/zombie_bioMaker.png");
    protected static final VillagerRegistry.VillagerCareer CAREER = new VillagerRegistry.VillagerCareer(PROFESSION, "md:BioMaker").addTrade(3, new ListItemForEmeralds(MoDropsItems.adaptive_egg, new PriceInfo(26, 33))).addTrade(1, new EmeraldForItems(Items.GOLD_INGOT, new PriceInfo(8, 9))).addTrade(1, new ListItemForEmeralds(MoDropsItems.biomatter, new PriceInfo(1, 1))).addTrade(2, new ListItemForEmeralds(MoDropsItems.compressed_biomatter, new PriceInfo(8, 10)))
    		.addTrade(2, new ListItemForEmeralds(Charcoal, new PriceInfo(1, 3)));   
    
    public static void onInit(FMLInitializationEvent event){
        VillagerRegistry.instance().register(PROFESSION);
        

    }
}

Well, you should add the code:

 

    public void onDeath(DamageSource par1DamageSource)

{

        if (!this.worldObj.isRemote)

        {

            EntityZombie entityzombie = new EntityZombie(this.worldObj);

            entityzombie.setLocationAndAngles(this.posX, this.posY, this.posZ, this.rotationYaw, this.rotationPitch);

            this.worldObj.spawnEntityInWorld(entityzombie);

            this.setDead();

        }

    }

Haven't tried it myself, but this should work. If it doesn't look into zombie meta data.