Please help ASAP

I'm working on a project and I've got everything under wraps except for the code.

What I'm doing is making five seperate pages that each have a different background, sound, and buttons that navigate to each area. I've got stop(); down pat. Each button should be going to another page using a mouse click, but when I test my movie I get this:

1120: Access of undefined property supra1b_btn.

Here is my action script:

stop();

supra1b_btn.addEventListener(MouseEvent.CLICK,navigate1);

function navigate1(event)

{

gotoAndPlay(1)

}

suprab2_btn.addEventListener(MouseEvent.CLICK,navigate2);

function navigate2(event)

{

gotoAndPlay(2)

}

An immediate resolutions to this problem would be greatly appreciated. I will upload the fla file if need be.