HP, DMG, HUD scripts problem

Hello. I have 3 scripts

1. enemyhealth ( player health and npc-zombie health )

 using UnityEngine;
 using System.Collections;
 
 public class enemyhealth : MonoBehaviour
 {
 
     public int health = 100;
 
     public virtual void otrzymaneObrazenia(float damage)
     {
 
         if (health > 0)
         {
 
             health -= (int)damage;
 
             if (health < 0)
             {
                 health = 0;
             }
         }
     }
 
 }

2. enemydamage only for zombie hand damage

 using UnityEngine;
 
 public class enemydamage : MonoBehaviour
 {
 
     public float damage = 10.0f;
 
 
     void OnTriggerEnter(Collider Enemy)
     {
         if (Enemy.gameObject.CompareTag("enemy"))
         {
             Enemy.gameObject.SendMessage("OnDamage", damage);
         }
     }
 }

3. And last script for player hud

 using UnityEngine;
 using UnityEngine.UI;
 
 public class ZdrowieGracza : enemyhealth {
 
 
     public Text zdrowieUI;
 
     public Image obrazeniaImage;
 
     private float predkoscBlysku = 5f;
 
 
     private Color kolorObrazenia = new Color (1f, 0f, 0f, 0.1f); 
 
 
     protected bool zadanoObrazenia = false;
 
 
     public override void otrzymaneObrazenia(float damage) {
         base.otrzymaneObrazenia(damage);
 
         zadanoObrazenia = true;
     }
     
     void Update(){
         if (zadanoObrazenia && obrazeniaImage != null) {
             obrazeniaImage.color = kolorObrazenia;
             zadanoObrazenia = false;
 
             setZdrowieUI();
         } else if(obrazeniaImage != null){
             obrazeniaImage.color = Color.Lerp(obrazeniaImage.color, Color.clear, predkoscBlysku * Time.deltaTime);
         }
     }
 
 
     private void setZdrowieUI(){
 
         if (zdrowieUI != null); 
     }
 }
 

Script is written in 2 languages (im sorry) but still my question is: where is mistake? When zombie attack player nothink happens with hp text. Maybe someone can help me?

Thanks in adwance.