The value is not reset for prefab.

Hi there.

I am facing a problems when I doing my game.

Its a defender game as the enemy hit your wall, your wall will be decreasing hp, till <=0, it destroyed. Everything is OK, the hp will reset to 10 when each play.

But after I made my wall into a prefab (it used to be just a object on scene), the Hp is not reset to the value I set (10) but continues from the previous play, and its not destroy itself anymore when Hp is <= 0...

Beginning of 1st time play, debug.log show hp = 10,

End of 1st time play, debug.log show hp = 5

Beginning of 2nd play, debug.log show hp = 5,

End of 2nd play, debug.log show hp = 0, (and its not destroying itself)

Beginning of 3rd play, debug.log show hp = 0,

End of 3rd play, debug.log show hp = -5,

This is my code for the Wall:

 using UnityEngine;
 using System.Collections;
 
 public class Wall : MonoBehaviour {
 
 
     public int castleHp = 10;
 
     // Use this for initialization
     void Start () 
     {
         castleHp = 10;
     }
 
     public void Damaging(int dmg)
     {
         Debug.Log (castleHp);
         castleHp = castleHp - dmg;
         Debug.Log (castleHp);
     }
         
 
     // Update is called once per frame
     void Update () 
     {
         if (castleHp <= 0)
             Destroy (gameObject);
     }
 }
 

And this is the code for one of the enemy:

 using UnityEngine;
 using System.Collections;
 
 public class EnemyAK : MonoBehaviour {
     
     public float lifeAK = 10;
     public float speed = 4.0f;
     bool shouldmove = true;
     public Wall wall;
     public int damage = 5;
 
 
     // Use this for initialization
     void Start ()
     {
         
     }
     
     void OnCollisionEnter (Collision col)
     {
         if (col.gameObject.tag == "CannonBall") 
         {
             lifeAK--;
         }
 
         if (col.gameObject.tag == "Walls") 
         {
             wall.Damaging (damage);
             shouldmove = false;
             Destroy (gameObject);
         }
     }
 
 
 
     // Update is called once per frame
     void FixedUpdate () 
     {
         //Destroy the object itself
         if (lifeAK == 0) 
         {
             Destroy (gameObject);
 
         }
 
         //walk/movement
         if(shouldmove == true)
         {
         transform.Translate(Vector3.left*Time.deltaTime*speed);
         }
     }
 }