How do I get my javascript to work?

this is what I have so far with the assets set up with the images. I’m using .png files for what that’s worth. This just doesn’t seems to work.

Thanks for any help

var playNormal : Texture2D;
var playHover : Texture2D;

function onMouseOver () {

guiTexture.texture = playHover;

}

function onMouseExit () {

guiTexture.texture = playNormal;

}

Please ensure posted code is correctly formatted. I don’t think there’s anything wrong with this code. Is this script a component of an object which also has a UI element or collider of some kind? Unity - Scripting API: MonoBehaviour.OnMouseOver()