Starting Coroutine from another script problem.

Hi, I'm having a problem trying to call an IEnumerator for a power up, I have been able to make my first power up script work and am using an almost exact copy of that code on this script but the co routine is not starting in the other script, any help would be appreciated, Thanks.

Power Up Script.

 using UnityEngine;
 using System.Collections;
 
 public class PowerUp2 : MonoBehaviour {
 
     GameObject powerUp2;
     public  AttackTrigger Buff;
     public GameObject Heavy;
     public GameObject Light;
 
     void Start()
     {
         Buff = Heavy.GetComponent<AttackTrigger>();
         Buff = Light.GetComponent<AttackTrigger>();
         powerUp2 = GameObject.FindGameObjectWithTag("powerUp2");
     }
     void OnTriggerEnter(Collider col)
     {
         if (col.gameObject.tag == "Player")
         {
             Buff.StartCoroutine("Buff2");
             Destroy(this.gameObject);
         }
     }
 }
 
 ## Script To Be Powered Up. 



 using UnityEngine;
 using System.Collections;
 
 public class AttackTrigger : MonoBehaviour {
 
     [SerializeField] int damageVal;
     [SerializeField] int critVal;
     HealthBloodKnight critFill;
     public GameObject player;
     public bool buffed;
 
     void Start() {
         critFill = player.GetComponent<HealthBloodKnight>();
         buffed = false;
     }
 
     void OnTriggerEnter(Collider col) {
 
         if(col.tag == "Enemy") {
             
                 col.gameObject.GetComponent<HealthEnemy>().TakeDamage(damageVal);
 
             if (!buffed && Random.value <= 0.2)
             {
                 col.gameObject.GetComponent<HealthEnemy>().TakeDamage(critVal);
                 print("Regcrit");
                 critFill.Crit();
             }
             if (buffed && Random.value <= 0.9)
             {
                 col.gameObject.GetComponent<HealthEnemy>().TakeDamage(critVal);
                 print("Bufcrit");
                 critFill.Crit();
             }
         }
     }
     public IEnumerator Buff2()
     {
         print("IamBuffed");
         buffed = true;
         yield return new WaitForSeconds(40f);
         buffed = false;
         yield return null;   
     } 
 }