I'm making a game where the player touches the screen and an object instantiates . However, I only want the object to instantiate if the Raycast hits an object that is on a specific layer (or of a specific tag if that is easier). I can get the ray to cast out and instantiate a prefab where I'd like it, but when I add in the section of checking for the layer, it sends me an error (NullReferenceException:Object reference not set to an instance of an object). This seems like such a simple thing but I can't get it to work. Any help would be GREATLY appreciated!

```
var box : Transform;

function Update ()
{

if (Input.GetMouseButtonDown(0))
{
if(roomController.noMore == false){
var hit : RaycastHit;
var mousePos : Vector3 = Input.mousePosition;
mousePos.z = 9;
var worldPos : Vector3 = camera.ScreenToWorldPoint(mousePos);
Debug.Log("Mouse pos: " + mousePos + " World Pos: " + worldPos + " Near Clip Plane: " + camera.nearClipPlane);

if(hit.collider.gameObject.layer == "Ground" && HierarchyType.collider != null){
clone = Instantiate(box, worldPos, Quaternion.identity);
noMore = true;
Destroy(this);
}

}
}
}

```