1120: access of undefined property of symbol

Hi,

I have a symbol (movieclip) named GirlPlayer and am coding simple keyboard movement. Every reference to GirlPlayer in the code produces the 1120: access of undefined property error. It is like the symbol is not being seen as a symbol. Any help appreciated. 

Donna

import flash.events.Event;
import flash.events.KeyboardEvent;

var leftarrow:Boolean = false;
var rightarrow:Boolean = false;
var uparrow:Boolean = false;
var downarrow:Boolean = false;
var previouskey:Number = 0;
var girlspeed:Number = 10;

//main program//
stage.addEventListener(KeyboardEvent.KEY_DOWN, onkeydown) ;
function onkeydown(e:KeyboardEvent){
if(e.keyCode == 37){leftarrow = true;}
if(e.keyCode == 38){uparrow = true;}
if(e.keyCode == 39){rightarrow = true;}
if(e.keyCode == 40){downarrow = true;}
}
stage.addEventListener(KeyboardEvent.KEY_UP, onkeyup) ;
function onkeyup(e:KeyboardEvent){
if(e.keyCode == 37){leftarrow = false;}
if(e.keyCode == 38){uparrow = false;}
if(e.keyCode == 39){rightarrow = false;}
if(e.keyCode == 40){downarrow = false;}
GirlPlayer.gotoAndPlay("idle");
previouskey = 0;
}

GirlPlayer.addEventListener(Event.ENTER_FRAME, girlenterframe);
function girlenterframe(e:Event){
if(leftarrow){
GirlPlayer.x -= girlspeed;
GirlPlayer.scaleX = -1;
if(previouskey !=37){GirlPlayer.gotoAndPlay("walk");}
previouskey = 37;
} etc.....