Mathf.Abs always returns 0

Hi everyone. I have a problem with my script in C#. Here the code:

 void FixedUpdate () {
  controls ();
  RaycastHit2D attr = Physics2D.Raycast (transform.position, sphere.position);
          if (attr.collider != null) {
              float dist_x = Mathf.Abs (attr.point.x - transform.position.x);
              float dist_y = Mathf.Abs (attr.point.y - transform.position.y);
              if (dist_x < 0.5f && Input.GetKey(KeyCode.Space)) {
                  attract (attr);
                  sphere.GetComponent<Rigidbody2D> ().AddForce (new Vector2 (boost_force, 0));
              }
          }
      }

The problem is that dist_x and dist_y are always set to 0. It's not reasonable, because the function Abs wants two float values and in this case I used two float values.