menu does not work, why?

This is my script of my menu, but it does not work, i’ve already checked the sintaxe, but everything is ok, can anyone help?

var IsQuitButoom = false;

function OnMouseEnter()
    renderer.material.color = Color.red;
}

function OnMouseExit()
{
    renderer.material.color = Color.white;
}

function OnMouseUp(){
    if (IsQuitButoom )
        Application.Quit();
    else
        Application.Loadlevel(1);
}

Does the object this script is attached to have a collider enabled ? Is its layer different from IgnoreRaycast ? Does it have a renderer ?