Help with "Kaboom" game programming, Unity first time user.

Okay so I'm making a game that is like Kaboom, and I'm having a problem with making an instance of my bomb object appear.

Here's the code for the bomb object it self:

using UnityEngine; using System.Collections;

public class Bomb : MonoBehaviour { public int moveSpeed = 60; Vector3 moveDirection = new Vector3(0,-1,0);

 // Use this for initialization
 void Start () 
 {
 
 }
 
 // Update is called once per frame
 void Update () 
 {
     Vector3 newPosition = moveDirection * (moveSpeed * Time.deltaTime);
     transform.position = transform.position + newPosition;
     
     if(newPosition.y > -40)
     {
         Destroy(transform.gameObject);
     }
 }
 
 void OnCollision(Collision collision)
 {
     Destroy(transform.gameObject);
 }

}

And I'm trying to get the enemy object to create a new instance of the bomb, here's the enemy object's code:

using UnityEngine; using System.Collections;

public class Enemy : MonoBehaviour { public int moveSpeed = 40; public bool isComputer = false; Vector3 computerDirection = Vector3.right; public bool onScreen = true; public Transform bomb;

 // Use this for initialization
 void Start () 
 {
 
 }
 
 // Update is called once per frame
 void Update () 
 {
     Vector3 newPosition = Vector3.zero;
     newPosition = computerDirection * (moveSpeed * Time.deltaTime);
     
     newPosition = newPosition + transform.position;
     
     if(newPosition.x > 20)
     {
         newPosition.x = 20;
         computerDirection.x *= -1;
     }
     
     else if(newPosition.x < -20)
     {
         newPosition.x = -20;
         computerDirection.x *= -1;
     }
     
     transform.position = newPosition;
     
     if(onScreen == true)
     {
         Transform newBomb = Instantiate(bomb,transform.position, transform.rotation) as Transform;
     }
 }

}

The thing that won't work is when I'm trying to create a new instance of the bomb while the enemy object is on screen, after the original bomb object is destroyed.

Any ideas??