Hello guys this is my enemies script it works very well, l now decided to add UI to it for the scores it started showing errors , am only new to unity pls help

using UnityEngine; using System.Collections; using UnityEngine.UI;

public class Differentball : MonoBehaviour {

 public GameObject[]spawnPoints;
 public GameObject Enemy;
 public Text countText;

 private int count;


 // Use this for initialization
 void Start () 
 {
     spawnPoints = GameObject.FindGameObjectsWithTag("spawn");
     count = 0;
     SetCountText ();
 }
 
 // Update is called once per frame
 void Update ()
 {
     
     GameObject[] enemies;
     enemies = GameObject.FindGameObjectsWithTag ("Enemy");

     if (enemies.Length >= 3) {
         print ("too many enemies on the dance floor");
     }
     else 
     {
         InvokeRepeating ("spawnEnemies", 1, 4f);
         count = count + 1;
         SetCountText ();
     }
 }

 void SetCountText ()
 {
     countText.text = " count ; " + count.ToString ();
 }

} void spawnEnemies ()

     int SpawnPos = Random.Range (0, (spawnPoints.Length - 0));

     Instantiate (Enemy, spawnPoints [SpawnPos].transform.position, transform.rotation);
     CancelInvoke ();
 }