camera not following target after reload

so I am using this camera script to follow the target but after i reload the game camera doesn't follow the target here's the script

 public Transform target;
 public float damping = 1;
 public float lookAheadFactor = 3;
 public float lookAheadReturnSpeed = 0.5f;
 public float lookAheadMoveThreshold = 0.1f;

 float offsetZ;
 Vector3 lastTargetPosition;
 Vector3 currentVelocity;
 Vector3 lookAheadPos;


 // Use this for initialization
 void Start()
 {
     
     GameObject player = GameObject.FindGameObjectWithTag("Player");
     target = player.transform;
     lastTargetPosition = target.position;
     offsetZ = (transform.position - target.position).z;
     transform.parent = null;

 }

 // Update is called once per frame
 void Update()
 {
     // only update lookahead pos if accelerating or changed direction
     float xMoveDelta =  (target.position - lastTargetPosition).y;

     bool updateLookAheadTarget = Mathf.Abs(xMoveDelta) > lookAheadMoveThreshold;

     if (updateLookAheadTarget)
     {
         lookAheadPos = lookAheadFactor * Vector3.up * Mathf.Sign(xMoveDelta);
     }
     else
     {
         lookAheadPos = Vector3.MoveTowards(lookAheadPos, Vector3.zero, Time.deltaTime * lookAheadReturnSpeed);
     }

     Vector3 aheadTargetPos = target.position + lookAheadPos + Vector3.forward * offsetZ;
     Vector3 newPos = Vector3.SmoothDamp(transform.position, aheadTargetPos, ref currentVelocity, damping);

     transform.position = newPos;

     lastTargetPosition = target.position;
 }