Help with GuiText flickering code.

Hello, I am trying to have my 3D Text in my game flicker. I have a script that has my lights flicker and I tried modifying it to fit the 3DText and it keeps coming up with the error: "NullReferenceException: Object reference not set to an instance of an object" Here is my code

 var GuiText1 : GameObject; 
 
 function Update () 
     {
         if ( Random.value > 0.9 ) //a random chance
         {
            if ( GuiText1.Renderer.enabled == true ) //if the light is on...
            {
              GuiText1.Renderer.enabled = false; //turn it off
            }
            else
            {
              GuiText1.Renderer.enabled = true; //turn it on
            }
         }
     }