Why RadioButton still selected?

When i start game again my radioButton selected. But in startProgram function i told : .selected=false;

Where the problem?

Attached .fla.

code:

import fl.controls.RadioButtonGroup;

var radioGroup1:RadioButtonGroup=new RadioButtonGroup("Coin Loss");
eagle_rb.group=radioGroup1;
tails_rb.group=radioGroup1;

var randomNumber:Number;
var points:Number=0;

function startProgram():void {
     eagle_rb.visible=true;
     tails_rb.visible=true;
     coin_mc.visible=true;
     eagle_rb.selected=false;
     tails_rb.selected=false;
     
     playAgain_btn.label="Play Again";
     coinToss_btn.label="Coin Toss";
     coinToss_btn.useHandCursor=true;
     playAgain_btn.useHandCursor=true;
     points_txt.text="0";
     eagle_rb.label="Eagle";
     tails_rb.label="Tails";
     error_txt.text="";

     playAgain_btn.visible=false;

     coinToss_btn.addEventListener(MouseEvent.CLICK, checkAnswer);

     playAgain_btn.visible=true;
     playAgain_btn.enabled=false;

     coinToss_btn.enabled=true;

     points=0;


}
startProgram();

function checkAnswer(event:MouseEvent):void {
     randomNumber=Math.random();
     trace(randomNumber);
     if (randomNumber<0.5) {
          coin_mc.gotoAndStop("eagle");
     } else {
          coin_mc.gotoAndStop("tails");
     }

     if (radioGroup1.selection==null) {
          error_txt.text="Need choose any answer!";
          return;
     } else if (radioGroup1.selection.label=="Eagle" && randomNumber<0.5) {
          error_txt.text=radioGroup1.selection.label+" - correct";
          points+=100;
          points_txt.text=String(points);
     } else if (radioGroup1.selection.label=="Eagle" && randomNumber>0.5) {
          error_txt.text=radioGroup1.selection.label+" - wrong";
          points-=100;
          points_txt.text=String(points);
     } else if (radioGroup1.selection.label=="Tails" && randomNumber>0.5) {
          error_txt.text=radioGroup1.selection.label+" - correct";
          points+=100;
          points_txt.text=String(points);
          coin_mc.gotoAndStop("tails");
     } else {
          error_txt.text=radioGroup1.selection.label+" - wrong";
          points-=100;
          points_txt.text=String(points);
     }


     if (points==500||points==-500) {
          gameResult();
     }
}

function gameResult():void {
     playAgain_btn.enabled=true;

     if (points==500) {
          message_txt.text="You are winner! You win 500 points!";
          coinToss_btn.enabled=false;
     } else if (points==-500) {
          message_txt.text="You are lost! You must pay 500 points;)";
          coinToss_btn.enabled=false;
     }

     playAgain_btn.addEventListener(MouseEvent.CLICK, playAgain);

     error_txt.text="";
     eagle_rb.visible=false;
     tails_rb.visible=false;
     coin_mc.visible=false;
}

function playAgain(event:MouseEvent):void {
     startProgram();

}