Help with corutines

using UnityEngine;
using System.Collections;

public class spawner : MonoBehaviour {

public GameObject obj1;
public GameObject obj2;
public GameObject obj3;
public GameObject obj4;
public GameObject obj5;
public bool spawned;
public float chooser;
public float sec;

void Start () {
	StartCoroutine (spawning ());
chooser = Random.Range (1, 5);
	sec = Random.Range (1, 5);
}

// Update is called once per frame
void Update () {

	spawning ();

}
IEnumerator spawning()
{

	if (chooser == 1) {
		Instantiate (obj1, transform.position, Quaternion.identity);
	}
	if (chooser == 2) {
		Instantiate (obj2, transform.position, Quaternion.identity);
	}
	if (chooser == 3) {
		Instantiate (obj3, transform.position, Quaternion.identity);
	}
	if (chooser == 4) {
		Instantiate (obj4, transform.position, Quaternion.identity);
	}
	if (chooser == 5) {
		Instantiate (obj5, transform.position, Quaternion.identity);
	}

	yield return new WaitForSeconds (2);
	chooser = Random.Range (1, 5);
	sec = Random.Range (1, 5);
}

}

This dosent work , it dosent spawn anything , can you pls help me ?

you have changed the value of chooser after you called the co-routine change it before