im trying to get 2 movieclips to put there self above eachother when the other reachs the bottom of the stage

but it does not meet line to line, the stage width is 480 and height 800

and it gets faster and faster

import flash.events.Event;

stop();

function repeatBackground():void {
	
	if(gameBackground01.y + gameBackgroundY > 799) {
		gameBackground01.y = -800;
	}
	if(gameBackground02.y + gameBackgroundY > 799) {
		gameBackground02.y = -800;
	}
	if(gameBackgroundY > 799) {
		gameBackgroundY = 0;
	}
	
	gameBackgroundY++;
}

function gameLoop(e:Event):void {
	if(gamePause == 0) {
		repeatBackground();
		gameBackground01.y += gameBackgroundY;
		gameBackground02.y += gameBackgroundY;
	} else {
		
	}
}

gameBackground01.x = 0;
gameBackground01.y = -800;
gameBackground02.x = 0;
gameBackground02.y = 0;

addEventListener(Event.ENTER_FRAME, gameLoop);

fixed it but it seems to lag in some spots

import flash.events.Event;

stop();

function repeatBackground():void {
	
	if(gameBackground01.y >= 800) {
		gameBackground01.y = -800;
	}
	if(gameBackground02.y >= 800) {
		gameBackground02.y = -800;
	}
	
	gameBackground01.y += 4;
	gameBackground02.y += 4;
}

function gameLoop(e:Event):void {
	if(gamePause == 0) {
		repeatBackground();
	} else {
		
	}
}

addEventListener(Event.ENTER_FRAME, gameLoop);

what if i wanted to add speed like setup a var speedVar:int = 2;

i tryed this but it wont work

gameBackground01.y += speedVar * 4;

gameBackground02.y += speedVar * 4;

it seems a little glitchy near the top after it repeats