I am a newbie. I need help about text fields

Hi, I am really new to actionscript ant trying to write a code which adds “adi” text input and “soyadi” text input into adisoyadi text field. But when I run the code, it gives me value 0. What Am I supposed to do now?

var adi:String;
var soyadi:String;
var adisoyadi:String= adi + soyadi;

submit_btn.addEventListener(MouseEvent.CLICK, bastir);
function bastir(event:MouseEvent):void
cikti_txt.text = adisoyadi;
adisoyadi=“adi” + soyadi ;