Error #1009

[Minnesnowta]

Hello All,

This is my first time posting, and I don't think it will be my last :-/

I am making a simple Ohm's Law Calculator and I am having some troubles. I haven't even progressed to writing the actual math functions on each of the frames because I am stuck :-(
First, here is the frame1 code:

volts_btn.addEventListener(MouseEvent.CLICK,voltsClick);
amps_btn.addEventListener(MouseEvent.CLICK,ampsClick);
ohms_btn.addEventListener(MouseEvent.CLICK,ohmsClick);
watts_btn.addEventListener(MouseEvent.CLICK,wattsClick);
intro_btn.addEventListener(MouseEvent.CLICK,introClick);

function introClick(event:MouseEvent){
	gotoAndStop(1);
}
function voltsClick(event:MouseEvent){
	gotoAndStop(2);
}
function ampsClick(event:MouseEvent){
	gotoAndStop(3);
}
function ohmsClick(event:MouseEvent){
	gotoAndStop(4);
}
function wattsClick(event:MouseEvent) {
	gotoAndStop(5);
}

Issues:
1.) See attached screenshot :
This is the intro frame (frame1)
I want the user to be able to select an output (which will advance to the corresponding frame) and then if they change their mind, they can select a different output and it will go to that frame. Currently, it will only allow me to ADVANCE to a frame and not go back (for example, if the user picks Ohms(frame4) first, it will not let you go to the Amps(frame3) or Volts(frame2). How can I change the code so that it lets me choose the output from each frame?

2.) This error is popping up when I test the file:

TypeError: Error #1009: Cannot access a property or method of a null object reference.
	at OhmsCalc_Scene1_fla::MainTimeline/frame1()[OhmsCalc_Scene1_fla.MainTimeline::frame1:1]

This is probably a really easy answer, so please let me know any solutions or suggestions that you may have.

THANKS!

[SLCMemento]

Its hard to say what exactly is causing that error with seeing your .fla. The best way to tackle errors like this, and learn how to get better at finding them, is to analyze and understand what the error message is telling you.

This error is saying, at frame 1, line 1 you are trying to reference an object that AT THAT TIME does not exist. At least it doesn't exist in the place your looking for it in (the main timeline).

So my guess is "volts_btn" is either not present or is named differently than "volts_btn" in your project. Check first to see if this button is there, and if there are any typos.

Make sense?

[Minnesnowta]

Yes, that makes sense... I am now seeing why I shouldn't have used frames to progress from screen to screen in the first place. I am going to follow user Mazoonist's suggestions (on a similar thread) and leave the whole "timeline" alone unless I want animation.

Thanks for the help!