NullReferenceException problem

hello i am making a game following a tutorial. i was here:

http://www.youtube.com/watch?v=O8-oZfi4utY&feature=channel_video_title

i was trying to make a line between my player and the enemy but it doesnt show up, i did exactly as he did and i got this.

NullReferenceException UnityEngine.Transform.get_position () (at C:/BuildAgent/work/6bc5f79e0a4296d6/Runtime/ExportGenerated/Editor/BaseClass.cs:771) EnemyAI.Update () (at Assets/hach and slash scripts/EnemyAI.cs:26)

please someone help me!

btw here is the enemy AI code:

 using UnityEngine;
 using System.Collections;
 
 public class EnemyAI : MonoBehaviour {
     public Transform target;
     public int moveSpeed;
     public int rotationSpeed;
     
     private Transform myTransform;
     
     void awake() {
         myTransform = transform;
     } 
 
     // Use this for initialization
     void Start () {
         GameObject go  = GameObject.FindGameObjectWithTag("Player");
         
         target = go.transform;
         
     
     }
     
     // Update is called once per frame
     void Update () {
         Debug.DrawLine(target.position, myTransform.position, Color.yellow);
         
         // look at target
         myTransform.rotation = Quaternion.Slerp(myTransform.rotation, Quaternion.LookRotation(target.position, myTransform.position), rotationSpeed * Time.deltaTime);
     
     }
 }

the error came in this line: Debug.DrawLine(target.position, myTransform.position, Color.yellow);