ReferenceError: Error #1074

This is probably a noob question so here is my code:
//---------------------------------------------------------------Variables
stop();
Key.initialize(stage);
time = 60;
Health = 106;
steps = 2;
endgamebool = false;
spriteX = 265;
score = 0;
dragons = 6;
DragonTimer = 0;
dragoni = 1;
endgame = false;
nextDragon = 100;
spriteY = 265;
arrowActive = false;
myTimer = new Timer(1000, 0);
ArrowClip:arrowMC = new arrowMC();
dragon1:dragonMC = new dragonMC();
dragon1Active = false;
dragon2:dragonMC = new dragonMC();
dragon2Active = false;
dragon3:dragonMC = new dragonMC();
dragon3Active = false;
dragon4:dragonMC = new dragonMC();
dragon4Active = false;
dragon5:dragonMC = new dragonMC();
dragon5Active = false;
dragon6:dragonMC = new dragonMC();
dragon6Active = false;
dragonActive:Array = new Array;
dragonActive[1] = 0;
dragonActive[2] = 0;
dragonActive[3] = 0;
dragonActive[4] = 0;
dragonActive[5] = 0;
dragonActive[6] = 0;
myTimer.start();
myTimer.addEventListener(TimerEvent.TIMER_COMPLETE, completeHandler);
myTimer.addEventListener(TimerEvent.TIMER,timerHandler);
//---------------------------------------------------------------Main Loop
countDown = function() {
if (endgamebool != true){
if(time <= 0) {
endgamebool = true;
}
//---------------------------------------------------------------Key Check
if (Key.isDown(Keyboard.RIGHT) && spriteX<510) {
spriteX += steps;
knight.legs.play();
} else if (Key.isDown(Keyboard.LEFT) && spriteX>40) {
spriteX -= steps;
knight.legs.play();
}
if (Key.isDown(Keyboard.UP) && arrowActive == false) {
knight.arms.play();
addChild(Arrow2Clip);
arrows = Arrow2Clip;
arrows.x = spriteX;
arrows.y = spriteY+50;
arrowActive = true;
}
//---------------------------------------------------------------Draw Dragon
if (DragonTimer >= nextDragon){
DragonTimer = 0;
nextDragon = (Math.random()200)+75;
if (dragoni==1 && dragonActive[dragoni]==0){
addChild(dragon1);
dragon1.y = 30 + (Math.random()15);
dragon1.x = 604
dragonActive[dragoni] = 1;
dragoni++;
}else if (dragoni==2 && dragonActive[dragoni]==0){
addChild(dragon2);
dragon2.y = 30 + (Math.random()15);
dragon2.x = 604
dragonActive[dragoni] = 1;
dragoni++;
}else if (dragoni==3 && dragonActive[dragoni]==0){
addChild(dragon3);
dragon3.y = 30 + (Math.random()15);
dragon3.x = 604
dragonActive[dragoni] = 1;
dragoni++;
}else if (dragoni==4 && dragonActive[dragoni]==0){
addChild(dragon4);
dragon4.y = 30 + (Math.random()15);
dragon4.x = 604
dragonActive[dragoni] = 1;
dragoni++;
}else if (dragoni==5 && dragonActive[dragoni]==0){
addChild(dragon5);
dragon5.y = 30 + (Math.random()15);
dragon5.x = 604
dragonActive[dragoni] = 1;
dragoni++;
}else if (dragoni==6 && dragonActive[dragoni]==0){
addChild(dragon6);
dragon6.y = 30 + (Math.random()15);
dragon6.x = 604
dragonActive[dragoni] = 1;
dragoni++;
}else{
dragoni=1;
}
}
DragonTimer++;
//---------------------------------------------------------------Update Dragon(s)
for (i=1;i<=dragons;i++){
if (dragonActive
==1){
dragonActive
=0;
if (i == 1 && dragon1.x>=0){
dragon1.x–;
dragonActive
=1;
}else if (i == 2 && dragon2.x>=0){
dragon2.x–;
dragonActive
=1;
}else if (i == 3 && dragon3.x>=0){
dragon3.x–;
dragonActive
=1;
}else if (i == 4 && dragon4.x>=0){
dragon4.x–;
dragonActive
=1;
}else if (i == 5 && dragon5.x>=0){
dragon5.x–;
dragonActive
=1;
}else if (i == 6 && dragon6.x>=0){
dragon6.x–;
dragonActive*=1;
}else{
dragonActive*=0;
}
}
if (dragonActive[1]==0 && dragon1.x < 600){
dragon1.x = 604;
dragon1.y = 30 + (Math.random()*15);
Health–;
}
if (dragonActive[2]==0 && dragon2.x < 600){
dragon2.x = 604;
dragon2.y = 30 + (Math.random()*15);
Health–;
}
if (dragonActive[3]==0 && dragon3.x < 600){
dragon3.x = 604;
dragon3.y = 30 + (Math.random()*15);
Health–;
}
if (dragonActive[4]==0 && dragon4.x < 600){
dragon4.x = 604;
dragon4.y = 30 + (Math.random()*15);
Health–;
}
if (dragonActive[5]==0 && dragon5.x < 600){
dragon5.x = 604;
dragon5.y = 30 + (Math.random()*15);
Health–;
}
if (dragonActive[6]==0 && dragon6.x < 600){
dragon6.x = 604;
dragon6.y = 30 + (Math.random()*15);
Health–;
}
}
//---------------------------------------------------------------Update Pawel
knight.x = spriteX;
knight.y = spriteY;
Health2.text = "Health: " + Health;
time2.text = "time: " + time;
//---------------------------------------------------------------Update Arrow
if (arrowActive == true){
if (arrows.hitTestObject(dragon1)){
dragonActive[1] = 0;
dragon1.x = 604;
score++;
}
if (arrows.hitTestObject(dragon2)){
dragonActive[2] = 0;
dragon2.x = 604;
score++;
}
if (arrows.hitTestObject(dragon3)){
dragonActive[3] = 0;
dragon3.x = 604;
score++;
}
if (arrows.hitTestObject(dragon4)){
dragonActive[4] = 0;
dragon4.x = 604;
score++;
}
if (arrows.hitTestObject(dragon5)){
dragonActive[5] = 0;
dragon5.x = 604;
score++;
}
if (arrows.hitTestObject(dragon6)){
dragonActive[6] = 0;
dragon6.x = 460;
score++;
}
score2.text = "Score: " + score;
if (arrows.y>-10){
arrows.y -= 3;
}else{
removeChild(arrows);
arrowActive = false;
}
}
}else{
Channel.stop();
removeChild(dragon1);
removeChild(dragon2);
removeChild(dragon3);
removeChild(dragon4);
removeChild(dragon5);
removeChild(dragon6);
myTimer.reset();
clearInterval(timerAS);
gotoAndStop(3);
}
};
timerAS = setInterval(countDown, 1);

I get the error
ReferenceError: Error #1074: Illegal write to read-only property arrowMC on global.
at PawelSprite_fla::MainTimeline/frame422()

Can anyone help? Thanks.