Linecast between character and camera doesn't ignoring Characters collider (layer).

I want to make camera get position from collision WITH WALL (in order to see character when he stand back to a wall). In order of this I: 1) create a layer and give this layer to my character (and all its children object) 2) casts a line (Physics.Linecast) between camera and character with invert mask with this layer, which I make invert.

But instead of IGNORE the players collider (via layerMask), Linecast somehow MAKE A COLLISION WITH CHARACTER'S own collider give this position to the camera, disregarding an exception of its layer. I try the whole week but I don't know what to do =( Please somebody help me fix this problem via Linecast (or Raycast).

 RaycastHit hit = new RaycastHit ();
 int layerMask = 1 << 8;
 layerMask = ~layerMask; //invert a bitmask - we want to collide against everything except layer 8
 
 if (Physics.Linecast(lookAt.position, camTransform.position, out hit, layerMask))
 {
     Debug.Log (hit.point);
     camTransform.position = hit.point;
 }