Rigidbody2d won't move in Newest Unity

I have created a rigidbody 2d in Unity 5.0.1f1. I then added a box collider 2d.

I attached the following script to the box:

pragma strict var Xforce : float; var Yforce : float; var temp : float;

function Start () {

}

function Update () { Xforce = 20f; Yforce = 20f; temp = Input.GetAxis("Horizontal");

   var rb = GetComponent.<Rigidbody2D>();
  
      rb.AddForce(new Vector2 (Xforce * temp,0));

}

However, when i press left and right, the value of temp scales from -1 to 1, but the object doesn't move.

Any ideas how to fix this!

Driving me crazy!

Roger