FLash: Error when trying to use setChildIndex and TweenLite to create a button rollOver effect

Answer 1

Based on what your trying to accomplished you don't have to manage depths. Essentially you can just add your rollover effect inside the shopButton and then once rolled over the shopButton, animate the glow. I udpated your code with the following:

import gs.TweenLite;
import fl.motion.easing.*;
import flash.display.MovieClip;


var shopButton:MovieClip;
var shopButtonRoll:MovieClip;

// Button - places the default state onto the stage
shopButton = new ShopButton();
shopButton.name = "shopButton";
shopButton.x = 262;
shopButton.y = 207;
shopButton.stop();
thumbsMov.addChild(shopButton);

// Button Glow - places rollOver state under the default and with 0 alpha
shopButtonRoll = new ShopButtonRoll();
shopButtonRoll.name = "shopButtonRoll";
shopButtonRoll.alpha = 0;
shopButton.addChild(shopButtonRoll);


// Listeners
shopButton.buttonMode = true;
shopButton.addEventListener(MouseEvent.MOUSE_UP, shopClick);
shopButton.addEventListener(MouseEvent.ROLL_OVER, shopOver);
shopButton.addEventListener(MouseEvent.ROLL_OUT, shopOff);

// Button Actions 
// shopOver should bring rollOver to top and animate to 100%

function shopOver(event:MouseEvent):void
{
     TweenLite.to(shopButtonRoll, 1, {alpha:1});
}
function shopOff(event:MouseEvent):void
{
    TweenLite.to(shopButtonRoll, 1, {alpha:0});
     // Code to animate back to 0 then change depth of rollOver to 0
}
function shopClick(event:MouseEvent):void
}
     trace("You clicked Shop");
}

Answer 2

When using TweenLite you can import their easing classes instead of the built in easing equations of Flash. Change your import to this:

import gs.TweenLite;
import gs.easing.*;

Then when you Tween your object, your syntax should look like this:

TweenLite.to(shopButtonRoll, 1, {alpha:1, ease:Strong.easeIn});