AS3 Editing event.target after being clicked befor executing gotoAndPlay("abc"); - actionscript-3

Question

Greetings stackoverflow members,
i have 3 animated movieclips nested in a movieclip. What I'm trying to do is to get the name of the instance clicked and edit it befor applying gotoAndPlay. I can get the name but when ever I try to edit it I'm getting the Error:
Symbol 'Buttons MC', Layer 'Actions', Frame 1, Line 30 1061: Call to a possibly undefined method gotoAndPlay through a reference with static type String.
Here's my code so far:
[Bindable] var targetName:String;
var _userInput:String = new String();
_userInput = targetName;
//array for buttons
var btnArray:Array = [INS_Btn1, INS_Btn2, INS_Btn3];
//add eventlistiners
for(var i:uint=0; i<btnArray.length; i++) {
btnArray[i].addEventListener(MouseEvent.ROLL_OVER, bRollover);
btnArray[i].addEventListener(MouseEvent.ROLL_OUT, bOut);
btnArray[i].addEventListener(MouseEvent.CLICK, bClick);
btnArray[i].buttonMode=true;
}
//btn over state
function bRollover(event:MouseEvent):void{
event.target.gotoAndPlay("Over");
}
//btn out state
function bOut(event:MouseEvent):void{
event.target.gotoAndPlay("Out");
}
//btn click state
function bClick(event:MouseEvent):void{
targetName = event.target +("_ani")
targetName.gotoAndPlay("Active");
}
What I want is that the MC clicked should go and play the animation of an onther MC. Best I should mention that I'm a beginner in AS3.

Answer 1

targetName is a String and of course you can't gotoAndPlay on a string :) Besides of that, event.target will return the object that you've clicked and not its name. And the targetName does not need to be bindable if you don't do anything special with it besides of this code.
So I assume you want a movieclip with the instance name INS_Btn1_ani to be played when you click on the INS_Btn1 button? First, make sure your buttons have the name property set (to make it easier, set the name as "INS_Btn1", "INS_Btn2" etc as well.
INS_Btn1.name = "INS_Btn1";
Then you would do it like that:
function bClick(event:MouseEvent):void
{
targetName = event.target.name + "_ani"; // this will become INS_Btn1 + _ani = INS_Btn1_ani
// Now you need to let the movieclip with the name "INS_Btn1_ani" play
this[targetName].gotoAndPlay("Active");
}

Answer 2

So after understanding the answer from Philarmon I've solved the problem. In case someone has the same/similar problem here's what I've done to get it working:
var targetName:String;
var _userInput:String = new String();
_userInput = targetName;
//array for buttons MCs
var btnArray:Array = [INS_btn1, INS_btn2];
var aniArray:Array = [INS_btn1_ani, INS_btn2_ani];
//add eventlistiners
for(var i:uint=0; i<btnArray.length; i++) {
btnArray[i].addEventListener(MouseEvent.ROLL_OVER, bRollover);
btnArray[i].addEventListener(MouseEvent.ROLL_OUT, bOut);
btnArray[i].addEventListener(MouseEvent.CLICK, bClick);
btnArray[i].buttonMode=true;
}
//btn over state
function bRollover(event:MouseEvent):void{
targetName = event.currentTarget.name + "_ani";
this[targetName].gotoAndPlay("Over");
}
//btn out state
function bOut(event:MouseEvent):void{
targetName = event.currentTarget.name + "_ani";
this[targetName].gotoAndPlay("Out");
}
//on clicked
function bClick(event:MouseEvent):void{
//add listeners for unclicked
for (var i:uint=0;i<btnArray.length; i++){
btnArray[i].addEventListener(MouseEvent.ROLL_OUT, bOut);
btnArray[i].addEventListener(MouseEvent.ROLL_OVER, bRollover);
//stopping animation
aniArray[i].gotoAndStop("Out");
}
//remove Eventlistener when clicked
event.target.removeEventListener(MouseEvent.ROLL_OUT, bOut);
event.target.removeEventListener(MouseEvent.ROLL_OVER, bRollover);
targetName = event.currentTarget.name + "_ani";
this[targetName].gotoAndStop("Active");
}
As you can see I've added a "sticky" function to keep the mc on click state.