Item Drop Help

I made a script that should be spawning Item1 when the enemy has 0 HP, maybe im missing something because nothing happens when they die…

using UnityEngine;
using System.Collections;

public class ItemDrop : MonoBehaviour {
	public Rigidbody Item1;
	public Rigidbody Item2;
	public Rigidbody Item3;
	public Transform monster;
	// Use this for initialization
	void Start () {
	
	}
	
	// Update is called once per frame
	void Update () {
		AttackandHP ZS = (AttackandHP)monster.GetComponent ("AttackandHP");
		if (ZS.curHealth == 0) {
			Item1Spawn();
		}
	}


	public void Item1Spawn() {
		Rigidbody clone;
		clone = Instantiate(Item1, monster.transform.position, monster.transform.rotation) as Rigidbody;
	}

}

Change

if (ZS.curHealth == 0) { 

to

if (ZS.curHealth <= 0) {

See if that helps. Chances are your monster has taken damage higher than his remaining HP and gotten into negative.