No renderer.enabled=false on grouped GameObject

Hi everyone,
if some of my Gameobjects are grouped in the hierarchy “GameObject.renderer.enabled = false;” is not working.
I just want hide some objects if the mouse is over an object. Is there anybody who can explain that to me?
Im still a beginner on Unity and in some points I dont understand the software. Here is my code snippet:

#pragma strict

var group1 : GameObject;
var group2 : GameObject;


function Start() {
 	group1 = GameObject.Find("GameObjectGroup1");
 	group2 = GameObject.Find("GameObjectGroup2");
}

function OnMouseOver() {
    group1.renderer.active = false;
    group2.renderer.active = true;
}


function OnMouseExit() {
    group1.renderer.active = true;
    group2.renderer.active = false;
}

it would be great if some of you have me some answers.
thanks!

group1.GetComponent().enabled = false;

This should work. Or simply

group1.active=false;

I believe the latter solution deactives the Collider and everything too though.

it works. thank you very much!
I just need more time to handle with unity;)