ActionScript 3.0 :: Thumbnail Buttons Not Working On Frame 2?

I'm working on putting together a portfolio website in Actionscript 3.0, and here's my situation: I have four main sections (Home, Works, Reel and Contact). When you first enter the website, it directs you to the Home content, which is on Frame 1. When you click on Works, it is intended to take you to Frame 2 - which it does just fine. On the works page, however, there is a frame to display large versions of the row of thumbnails along the bottom. Frame 2 automatically displays the large image of the first thumbnail, but the second thumbnail redirects you to Frame 3, which is identical, except it replaces the large image of the first thumbnail with the large image of the second thumbnail - and so on and so forth.

The thing is, when I get to Frame 2, my thumbnail buttons aren't working and I get this error:
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at Portfolio_Site_03_fla::MainTimeline/frame1()

What I'm getting from this error is that it essentially doesn't recognize my thumbnail buttons because they do not exist on frame 1. I even attempted to move the keyframes with the thumbnail buttons on them to frame 1 and everything was working just fine, except for the fact that I had big thumbnail buttons all over my home page which I do not want to be there. For reference, here is my AS code:

ActionScript Code:
stop();
import flash.events.MouseEvent;
import flash.net.URLRequest;
//---Home Button---\
Home_Button.addEventListener(MouseEvent.CLICK,hClick);
function hClick(event:MouseEvent):void{
[Code] .....

How can I resolve my situation and get my buttons to do what I want them to do? My only guess would be that I'd need to make a new scene, but wasn't that one of the major points of AS 3.0?