Random.range game object destroying itself before reaching destroy position.Please help.

I have started cloning objects from a random range on my y axis.but they are getting destroyed before reaching the destroy position.Need help,really fast.

here is the generator script;

 using UnityEngine;
 using System.Collections;

 public class generate : MonoBehaviour {
 public GameObject clone,asteroid1;
 public GameObject[] asc= new GameObject[3];
 
 public float createrate = 0.5f;
 private float nextcreate = 0.0f;
 
 // Use this for initialization
 void Start () {
     
 }
 
 // Update is called once per frame
 void Update () 
 {
     if (Time.time > nextcreate) 
         
     {
         nextcreate = Time.time + 1.2f;
         clone = Instantiate (asc[Random.Range(0,3)] , transform.position, transform.rotation) as GameObject;// create a duplicste of an object in the position of the "clone". 
         //Vector3 position = new Vector3(Random.Range(-10.0F, 10.0F), 0, Random.Range(-10.0F, 10.0F));
         clone.transform.position = new Vector3 (10.875F, Random.Range (6.775F, -7.15F), 0);        
         }
     }
 }

Destroy Script;

 using UnityEngine;
 using System.Collections;

 public class gameover :  MonoBehaviour
 {
 public GameObject colt2;
 // Use this for initialization
 void Start () {
 
 }
 
 // Update is called once per frame
 void Update () {
 
 }
 void OnCollisionEnter2D(Collision2D colt2)
 {
     
     if (colt2.gameObject.tag == "border") 
     {
         Application.LoadLevel("game_over");
     }
     if (colt2.gameObject.tag == "ast") 
     {
         Application.LoadLevel("game_over");
     }
 }
 }