Buttons don't work if united into MovieClip

Question

I have an animated image collage with 10+ images. It is brought in into the main stage as a united mc. Each image has to act as a button which links to a labeled section in the flash file.
I understand that I can not write AS3 on the main stage as I am unable to specify the instance name for each button since they all are brought as a united mc and only that mc is available as an instance.
So I go inside the mc to the level where I can select each button, give the button an instance name and then put the following code on the AS3 layer inside the mc level where all the images/buttons are assembled as a collage:
my_btn1.addEventListener(MouseEvent.CLICK,my_btn1_Down);
my_btn1_Down(event:MouseEvent): void {
MovieClip(parent.parent.parent.parent.parent.parent.parent.parent.parent.parent).gotoAndPl ay("icysophistication");
I started with just one parent and kept on adding them up to see if it will change the result, but unfortunately all the same "Error #1009: Cannot access a property or method of a null object reference."
you can view the site at www.888acolyte.com
It is still under the development and will take a min to load then wait for the image collage to appear. Those images are the ones which i would like to make into buttons.

Answer 1

There should be nothing preventing you from having the code on the main timeline.  You just need to target the buttons thru the mc instance name...
your_mc.my_btn1.addEventListener(MouseEvent.CLICK,my_btn1_Down);
function my_btn1_Down(event:MouseEvent): void {
    this.gotoAndPlay("icysophistication");
And if you name your buttons to match the frame labels, you can have all the buttons share the same event handler function...
your_mc.icysophistication.addEventListener(MouseEvent.CLICK, btnClick);
your_mc.spicysophistication.addEventListener(MouseEvent.CLICK, btnClick);
etc....
function btnClick(event:MouseEvent): void {
    this.gotoAndPlay(evt.currentTarget.name);