I need some serious help!

Ok I'm not sure what the problem really is but maybe someone can help

I don't get a script error I just get an error in output:

TypeError: Error #1010: A term is undefined and has no properties.
    at Gallery_fla::MainTimeline/frame1()

From my looking at it, there is nothing wrong with the timeline but I have my script on the timeline in an actions layer:

My code:

//left button
left.addEventListener(MouseEvent.MOUSE_DOWN, lmd);
left.addEventListener(MouseEvent.MOUSE_UP, lmu);
left.addEventListener(MouseEvent.MOUSE_OUT, lml);
var lefttimer = new Timer( 12 );

lefttimer.addEventListener(TimerEvent.TIMER, lefttick);

function lmd(mouseEvent:MouseEvent):void {
    lefttimer.start();
}

function lmu(mouseEvent:MouseEvent):void {
    lefttimer.stop();
}

function lml(mouseEvent:MouseEvent):void {
    lefttimer.stop();
}

function lefttick(timerEvent:TimerEvent):void {
    if (strip.x > -2578.2) {
        strip.x += 3;
    }
}

//right button
right.addEventListener(MouseEvent.MOUSE_DOWN, rmd);
right.addEventListener(MouseEvent.MOUSE_UP, rmu);
right.addEventListener(MouseEvent.MOUSE_OUT, rml);
var righttimer = new Timer( 12 );

righttimer.addEventListener(TimerEvent.TIMER, righttick);

function rmd(mouseEvent:MouseEvent):void {
    righttimer.start();
}

function rmu(mouseEvent:MouseEvent):void {
    righttimer.stop();
}

function rml(mouseEvent:MouseEvent):void {
    righttimer.stop();
}

function righttick(timerEvent:TimerEvent):void {
    if (strip.x < 117){
        strip.x -= 3;
    }
}

//photo adding
strip.a_g_but.addEventListener(MouseEvent.CLICK, agbut);

function agbut(mouseEvent:MouseEvent):void {
    photo.text = "Alpacas and Goats";
    vloader.visible = false;
    hloader.visible = true;
    hloader.source = "files/alpacas_goats.jpg";
}

strip.an_g_but.addEventListener(MouseEvent.CLICK, angbut);

function angbut(mouseEvent:MouseEvent):void {
    photo.text = "Angora Goats";
    vloader.visible = false;
    hloader.visible = true;
    hloader.source = "files/angora_goats.jpg";
}

strip.b_e_but.addEventListener(MouseEvent.CLICK, bebut);

function bebut(mouseEvent:MouseEvent):void {
    photo.text = "Bird Enclosure";
    vloader.visible = false;
    hloader.visible = true;
    hloader.source = "files/bird_enclosure.jpg";
}

strip.c_but.addEventListener(MouseEvent.CLICK, cbut);

function cbut(mouseEvent:MouseEvent):void {
    photo.text = "Cockatoo";
    vloader.visible = true;
    hloader.visible = false;
    vloader.source = "files/cockatoo.jpg";
}

strip.c2_but.addEventListener(MouseEvent.CLICK,c2but);

function c2but(mouseEvent:MouseEvent):void {
    photo.text = "Closup of the Cockatoo";
    vloader.visible = false;
    hloader.visible = true;
    hloader.source = "files/cockatoo2.jpg";
}

strip.d_but.addEventListener(MouseEvent.CLICK, dbut);

function dbut(mouseEvent:MouseEvent):void {
    photo.text = "Deer";
    vloader.visible = false;
    hloader.visible = true;
    hloader.source = "files/deer.jpg";
}

strip.de_but.addEventListener(MouseEvent.CLICK, debut);

function debut(mouseEvent:MouseEvent):void {
    photo.text = "Ducks";
    vloader.visible = false;
    hloader.visible = true;
    hloader.source = "files/ducks.jpg";
}

strip.e_but.addEventListener(MouseEvent.CLICK, ebut);

function ebut(mouseEvent:MouseEvent):void {
    photo.text = "Entrance";
    vloader.visible = true;
    hloader.visible = false;
    vloader.source = "files/entrance.jpg";
}

What is wrong??