Mouseclick event issue

When I run the file and try to shoot the zombies, none of them are clickable. I really can’t tell what I have done wrong here.
Here is my code:

stage.addEventListener(Event.ENTER_FRAME, moveBullseye);

function moveBullseye(event:Event) {
bullseye_mc.x=mouseX;
bullseye_mc.y=mouseY;
txtscore.text = 'Score: '+score;
txtlives.text = 'Lives: '+lives;
}
stage.addEventListener(Event.ENTER_FRAME, movehands);

function movehands(event:Event) {
hands.x=mouseX;

}
import flash.events.;
import flash.display.MovieClip;
import flash.events.MouseEvent;
import fl.transitions.Tween;
import fl.transitions.easing.
;
zombie1.addEventListener(Event.ENTER_FRAME, growzombie);
zombie2.addEventListener(Event.ENTER_FRAME, growzombie);
zombie3.addEventListener(Event.ENTER_FRAME, growzombie);
zombie4.addEventListener(Event.ENTER_FRAME, growzombie);

function growzombie(event:Event):void {
zombie1.scaleX += .001;
zombie1.scaleY += .001;
zombie2.scaleX += .001;
zombie2.scaleY += .001;
zombie3.scaleX += .0001;
zombie3.scaleY += .0001;
zombie4.scaleX += .0001;
zombie4.scaleY += .0001;
}
zombie1.addEventListener(Event.ENTER_FRAME, fadezombie);
zombie2.addEventListener(Event.ENTER_FRAME, fadezombie);
zombie3.addEventListener(Event.ENTER_FRAME, fadezombie);
zombie4.addEventListener(Event.ENTER_FRAME, fadezombie);

function fadezombie(event:Event):void {
zombie1.scaleY += .001;
zombie2.scaleX += .001;
zombie2.scaleY += .001;
zombie3.scaleX += .0001;
zombie3.scaleY += .0001;
zombie4.scaleX += .0001;
zombie4.scaleY += .0001;
}
var aflashTimer:Timer = new Timer(18000,1);
aflashTimer.addEventListener(TimerEvent.TIMER, aonTime);

aflashTimer.start()

function aonTime(evt:TimerEvent):void{
zombie1.gotoAndStop(3);
zombie2.gotoAndStop(3);
lives–;

}
var bflashTimer:Timer = new Timer(25000,1);
bflashTimer.addEventListener(TimerEvent.TIMER, bonTime);

bflashTimer.start()

function onTime(evt:TimerEvent):void{
zombie3.gotoAndStop(3);
zombie4.gotoAndStop(3);
lives–;

}

import flash.events.MouseEvent;

zombie1.addEventListener(MouseEvent.CLICK, hitzombie);
zombie2.addEventListener(MouseEvent.CLICK, hitzombie);
zombie3.addEventListener(MouseEvent.CLICK, hitzombie);
zombie4.addEventListener(MouseEvent.CLICK, hitzombie);

function hitzombie(evt:MouseEvent):void
{
evt.currentTarget.play(1);
score += 3;
}