1120: Access of undefined property purple1_btn

Greetings,

I have been trying to find the answer for a while, but they all say the same thing and I have already fixed my instance.

You are supposed to be able to click on the button and go to the next "page" (frame). I DO already have names for my instance. The button name is purple_btn and the instance is purple1_btn.

Here is my code.

stop();

purple1_btn.addEventListener(MouseEvent.CLICK, fl_ClickToGoToAndPlayFromFrame_4);

function fl_ClickToGoToAndPlayFromFrame_4(event:MouseEvent):void

{

  gotoAndPlay(21);

}

My friend and I have tried moving things around and changing layers and so on, but nothing has been working, so any help would be greatly appreciated.

Thanks in advance.