Having trouble using SendMessage

I'm trying to use SendMessage in conjunction with OnCollisionEnter to detect enemies being hit, and applying damage to them. Here is my code.

• Attached to player's weapon

using UnityEngine; using System.Collections;

public class enemyKill : MonoBehaviour {

 void Start () {
 
 }
 
 
 void Update () {


 
 }
 void OnCollisionEnter(Collision hit)
 {
     if(hit.gameObject.tag == "enemy"){
         //detects if object hit was an enemy
     SendMessage("applyDMG");
         //sends messaage
     print("you hit him");
         //bugtesting that collision was detected
         }

}

• Attached to enemy

using UnityEngine; using System.Collections;

public class receiveDamage : MonoBehaviour {

 void Start () {

 }

 void applyDMG(){
     //receives message? not 100% how this works pls help
             print("DMG message received");
     //bugtesting message received
     }
 }

When the player's sword collides with an enemy, the message is not received, but "you hit him" is printed in the console, sop the collision is working.

Please help, thanks.