Adding a "Die-Event" to my Enemy-Script with OnCollisionEnter

I have an EnemyScript, that lets my animated Enemy target and chase the player from certain distances and returns to a set Startpoint, if the Playerdistance is to high.

Everything works fine(more or less), but now i want my enemy to "die"(eg play a certain Animation) if he is hit with the weapon.(hit Once, no facy health scripts, just a one hitter).

I Tried OnCollisionEnter with a Condition that the colliding GameObject has to be tagged "Weapon", (The Weapon has a nonkinematic Rigidbidy), but the Enemy simply does not react to my Player hitting it with the Weapon.

Any Ideas would be highly appreciated, Im a total Noob in Scripting(3D Artist) and would need Easy-to-follow-Instructions(and an explaination what i did wrong would be great)

Here´s my Script:

 using UnityEngine;
 using System.Collections;
 
 public class EnemyNew : MonoBehaviour {
 
     public AnimationClip IdleAnim;
     public AnimationClip WakeupAnim;
     public AnimationClip TargetAnim;
     public AnimationClip ChaseAnim;
     public AnimationClip FightAnim;
     public AnimationClip AttackAnim1;
     public AnimationClip AttackAnim2;
     public AnimationClip WalkAnim;
     public AnimationClip DieAnim;
 
     private Animation _animation;
 
 
     public Transform StartPoint;
     public Transform player;
     public Transform SelfRotationReferencePointLeftShoulder;
 
     public float RotationDamping;
     public float MoveSpeed;
     public float WakeUpAnimSpeed = 1;
 
     public float PlayerDistance;
     public float StartDistance;
     public float EnemyRotation;
 
     void Start()
     {
         _animation = GetComponent<Animation>();
         _animation.Play (IdleAnim.name);
         _animation[WakeupAnim.name].speed = WakeUpAnimSpeed;
     }
 
     void Update ()
     {
         PlayerDistance = Vector3.Distance (player.position, transform.position);
 
         StartDistance = Vector3.Distance (StartPoint.position, transform.position);
 
 
 
         if (PlayerDistance < 12f) 
         {
             Target();
         }
 
         if (PlayerDistance < 10f) 
         {
             if(PlayerDistance > 3f)
             {
             Chase();
             }
         }
         if (PlayerDistance < 3f) 
         {
             Fight();
 
         }
 
         if (PlayerDistance < 2.8f) 
         {
             Attack();
         }
 
         if (PlayerDistance > 12f) 
         {
             if(StartDistance < 0.1f)
             {
             Return();
             }
         }
 
         if (StartDistance < 0.1f) 
         
         {
             IsReturned();
         }
 
 
 
     }
     void OnCollisionEnter(Collision Col)
     {
         if (Col.gameObject.tag == "Weapon") 
         
         {
             _animation.Play(DieAnim.name);
         }
     }
     void Target()
     {
 
         _animation.CrossFade (WakeupAnim.name);
         _animation.CrossFade (TargetAnim.name);
         Quaternion rotation = Quaternion.LookRotation (player.position - transform.position);
         transform.rotation = Quaternion.Slerp (transform.rotation, rotation, Time.deltaTime * RotationDamping);
 
     }
     void WakeUp()
 
     {
         _animation.CrossFade (WakeupAnim.name);
         _animation.CrossFadeQueued (TargetAnim.name);
 
         Quaternion rotation = Quaternion.LookRotation (player.position - transform.position);
         transform.rotation = Quaternion.Slerp (transform.rotation, rotation, Time.deltaTime * RotationDamping);
     }
 
 
     void Chase()
     {
         Quaternion rotation = Quaternion.LookRotation (player.position - transform.position);
         transform.rotation = Quaternion.Slerp (transform.rotation, rotation, Time.deltaTime * RotationDamping);
         transform.Translate (Vector3.forward * MoveSpeed * Time.deltaTime);
 
         _animation.CrossFade (ChaseAnim.name);
 
     }
 
     void Fight()
 
     {
         Quaternion rotation = Quaternion.LookRotation (player.position - transform.position);
         transform.rotation = Quaternion.Slerp (transform.rotation, rotation, Time.deltaTime * RotationDamping);
 
 
         _animation.CrossFade (FightAnim.name);
     }
 
     void Attack()
     {
         if (SelfRotationReferencePointLeftShoulder.transform.position.x > 0f) 
         {
             _animation.Play (AttackAnim1.name);
 
         }
     }
 
     void Return()
     {
         Quaternion rotation = Quaternion.LookRotation (StartPoint.position - transform.position);
         transform.rotation = Quaternion.Slerp (transform.rotation, rotation, Time.deltaTime * RotationDamping);
         transform.Translate (Vector3.forward * MoveSpeed * Time.deltaTime);
 
         _animation.CrossFade (WalkAnim.name);
     }
 
     void IsReturned()
     {
         transform.Translate(0, 0, 0);
         transform.rotation = Quaternion.identity;
 
         _animation.CrossFade(DieAnim.name);
         _animation.CrossFade(IdleAnim.name);
     }
 }