Script doesnt work

hey guys i was following the tornado twins tut but this script doesnt work at all Way?? thank you

var isQuitButton = false;

function OnMouseEnter () 
{
     //change the color of the text
     renderer.material.color = Color.green;
}

function OnMouseExit () 
{
     //change the color of the text
     renderer.material.color = Color.white;
}

function OnMouseUp () 
{
     //are we dealing with a quit button?
     if( isQuitButton )
    {
         //quit the game
         Application.Quit();
    }
    else
    {
          //load level
          Application.LoadLevel(1);
    }
}

Are you adding this script to a guiText? If you are did you remember to add a boxcollider to

the guiText? If you did not it wont register OnMouseUp, OnMouseOver or OnMouseExit.