My LayerMask is not working

The spotted bool is not activating with the layer I set it to operate with. It doesn't activate at all when I apply a LayerMask, please help me figure out what is the issue. If you need more info let me know.

 public Transform sightStart, sightEnd; 
 public bool spotted= false;


 // Update is called once per frame
 void Update () {
     Raycasting ();
     behaviors (); 
 }

 void Raycasting() 
 {
     Debug.DrawLine (sightStart.position, sightEnd.position, Color.red); 
     spotted = Physics2D.Linecast (sightStart.position, sightEnd.position, 1 << LayerMask.NameToLayer("Positive"));
 }