Problematic scripting

function Start () {
    thoughtText.font.material.color.a = 0;
}

var thoughtText : GUIText;

function OnTriggerEnter (other : Collider) {
    if (other.gameObject.name == "Shed Thoughts"){
        thoughtText.text = "Oh lord";
        thoughtText.font.material.color.a += Time.deltaTime;
        Debug.Log("Works better");
    }
}

function OnTriggerExit (other : Collider) {
    thoughtText.text = "";
}