Help needed with AS2

Hey, I am trying to program a small game on flash for a project but it’s been a while since I used actionscript.
I have most elements working correctly but I can’t seem to get this change colour function to work.
Here’s the code:

colorNo = 1;

_root.onEnterFrame = function ()
{

if (Key.isDown(Key.UP)){
colorNo +=1};
if (Key.isDown(Key.DOWN)){
colorNo -=1};

if (colorNo < 1){
colorNo = 6};
if (colorNo > 6){
colorNo = 1};

if (colorNo = 1){
_root.bubble.gotoAndPlay(“red”)};
if (colorNo = 2){
_root.bubble.gotoAndPlay(“blue”)};
if (colorNo = 3){
_root.bubble.gotoAndPlay(“green”)};
if (colorNo = 4){
_root.bubble.gotoAndPlay(“purple”)};
if (colorNo = 5){
_root.bubble.gotoAndPlay(“orange”)};
if (colorNo = 6){
_root.bubble.gotoAndPlay(“yellow”)};

color_txt.text="colorNo = “+colorNo+” ";

}

I’ve tried dozens of different ways to do this but there’s always some error.
This is the simplest method I’ve tried but for some reason the colour value goes straight to the maximum value.
I can’t just set the rgb values either because in the end product it will have to switch between animations.

Any ideas??