Loading a PNG as a Texture (JavaScript)

#pragma strict

var imageCount : int = 0;
var imageNameBase : String = "";
var imageNameZeroPadding : int = 0;

var changeInterval : float = 0.06;  
var isRunning = false;
var isLooping = false;

private var texture : Texture = null;

function PlayRocket () {
    isRunning = true;
}

function Start () {
    var isRunning = false;
    var fileName : String = imageNameBase + ZeroPad(0,imageNameZeroPadding);
    texture = Resources.Load(fileName);
}

function Update () {
    if( isRunning == true) {    
        PNGAnimation ();
    }
}

function PNGAnimation () {
    var index : int = Time.time/changeInterval;
    index = index % imageCount;
    var fileName : String = imageNameBase + ZeroPad(index,imageNameZeroPadding);
    Resources.UnloadAsset(texture);
    texture = Resources.Load(fileName);
    renderer.material.mainTexture = texture;


    if ( index == imageCount-1){
        Debug.Log("End of Animation");
        Debug.LogWarning("End of Animation");
        if( isLooping == false){
            isRunning = false;
        }
        fileName = imageNameBase + ZeroPad(0,imageNameZeroPadding);         
        Resources.UnloadAsset(texture);
        texture = Resources.Load(fileName);
        renderer.material.mainTexture = texture;
    }
}

function ZeroPad(number : int, size : int) {
    var numberString : String = number.ToString();
    while (numberString.Length 

}