Zoom / enlarge gameobject ?

Hye !
I am looking for code that would allow me to expand a game object when I rolls the mouse.
i found this :

var scaleFactor : float = 1.5f;

function OnMouseEnter ()
{
   transform.scale *= scaleFactor;
}

function OnMouseExit ()
{
   transform.scale /= scaleFactor;
}

But it doesn’t work, when i put the script on my game object i have this error :
NullReferenceExeption: Object reference not set to an instance of an object

Somebody have an idea ?

PS : really sorry for my bad english.

It should be transform.localScale instead of transform.scale - despite this error message seems to refer to another problem. Anyway, fix the code and try again.

Yep, it works fine !
Thank you very much, for your help and your time !