Need Help : Going Back frames!

1

Hello all

So i am building a portfolio and have my main stage with three frames, the first is my navigation section with 2 buttons

button 1 sends the playhead to frame2 and button sends the playhead to frame3 etc

here is the code
<a>stop();

ShowReel_btn.addEventListener(MouseEvent.MOUSE_DOWN , Showreel)

function Showreel(evt:MouseEvent) : void {
gotoAndStop(2)
}

VizualTech_btn.addEventListener(MouseEvent.MOUSE_DOWN , Viz)

function Viz(evt:MouseEvent) : void {
gotoAndStop(3);
}</a>

and that works

now on frames 2 and 3 i have a button that has this code

<a>Home_btn.addEventListener(MouseEvent.CLICK , goback );

function goback(evt:MouseEvent) : void {
gotoAndPlay(1)
} </a>

and it works but gives me this error :

TypeError: Error #1009: Cannot access a property or method of a null object reference.
at WorkingMain_fla::MainTimeline/frame1()
at flash.display::MovieClip/gotoAndPlay()
at WorkingMain_fla::MainTimeline/goback()

it does put me back on to the frame 1 but the buttons dont work after that…

…this wouldnt have happened in AS 2.0

anyidea how to get around this please ?