Error #1009 When trying to return to frame 1

Question

I am getting an error #1009 "Cannot access a property or method of a null object reference."  Frame one is not empty. I have buttons in frame 1 that use this code to gotoAndStop on frames 5,10,25...they work just fine.  I only get the error when trying to return to frame 1 from those locations. Can someone help me out with this issue?
stop();
btn_rtni.addEventListener(MouseEvent.CLICK, mainBooth_1);
function mainBooth_i(MouseEvent):void {
            gotoAndStop(1);

Answer 1

I allowed "debugging" and this is the error that appreared.  But I still don't get what the problem is or how to correct it.  Most of my content is in frame 1, so I don't understand why it's returning null.  Any advice would be appreciated.
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at VB_NABR_fla::MainTimeline/frame1()[VB_NABR_fla.MainTimeline::frame1:93]