OnClickListener on AlertDIalog doesn't work

Question

I need to create a multi-player game on-line in Java and for Android platform. It looks like a western game, and this class should handle the duel between two or more players. When a user press the "BANG" button, the app should send a message to the server, but it doesn't even print the message "****BANG PRESSED****" Someone please help me, this is a project for my university

package com.example.root.gbu;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.os.SystemClock;
import android.widget.ImageView;

public class DuelFrame {

    private Context context;
    private long startTime;
    private long endTime;
    private boolean timeToShot=false;
    private ImageView image;
    private AlertDialog alertDialog;

    public DuelFrame(String enemy, Context context){
        this.context = context;
        alertDialog = new AlertDialog.Builder(context).create();
        alertDialog.setTitle("Duel against " + enemy);
        alertDialog.setButton(Dialog.BUTTON_POSITIVE,"OK",new DialogInterface.OnClickListener(){

            @Override
            public void onClick(DialogInterface dialog, int which) {
                System.out.println("***BANG PRESSED****");
                if(timeToShot) {
                    endTime = SystemClock.elapsedRealtimeNanos();
                    ConnectionStream.getOut().println("TIME:" + String.valueOf(endTime - startTime));
                }
                else
                    ConnectionStream.getOut().println("TIME:LOSE");
            }
        });
        image = new ImageView(context);
        image.setImageResource(R.drawable.duel_start);
        alertDialog.setView(image);
    }

    public void start(){
        ((Activity)context).runOnUiThread(new Runnable(){//mostro la finestra
            @Override
            public void run(){
                alertDialog.show();
            }
        });
        new java.util.Timer().schedule(//timer per cambiare l'immagine
                new java.util.TimerTask() {
                    @Override
                    public void run() {
                        ((Activity)context).runOnUiThread(new Runnable(){
                            @Override
                            public void run(){
                                image.getLayoutParams().height = image.getHeight();
                                image.getLayoutParams().width = image.getWidth();
                                image.setImageResource(R.drawable.bang);
                                startTime = SystemClock.elapsedRealtimeNanos();
                                timeToShot = true;
                            }
                        });
                    }
                }, 3000);
    }

    public void cancel(){
        ((Activity)context).runOnUiThread(new Runnable(){
            @Override
            public void run(){
                //alertDialog.dismiss();
                //alertDialog.cancel();
                alertDialog.hide();
            }
        });
    }
}

The class that calls DuelFrame looks like

public class GameActivity extends AppCompatActivity {

    private DuelFrame duelFrame;
    ....

    public void startDuel(final String enemy){
        duelFrame = new DuelFrame(enemy, this);
        duelFrame.start();
    }

    public void endDuel(){
        if(duelFrame!=null) {
            duelFrame.cancel();
            duelFrame = null;
        }
    }
    ....
}

And there is a class called Listener which is a thread that execute server's commands in this way

for (messages = ConnectionStream.getIn().readLine().split(":");
             !messages[0].equals("ENDGAME"); messages = (debug = ConnectionStream.getIn().readLine()).split(":")) {
            System.out.println(i++ + ": " + debug);
            switch (messages[0]) {//scelgo cosa fare a seconda del messaggio
                case "ADD"://ADD:NOMEGIOCATORE:NODODIPARTENZA:WHITE/BLACK
                    game.login(messages[1], messages[3].equals("white"));
                    game.movePlayer(game.getPlayer(messages[1]), messages[2]);
                    break;
                case "MOVE"://MOVE:GIOCATORE:NODO
                    game.movePlayer(game.getPlayer(messages[1]), messages[2]);
                    break;
                case "REMOVE"://REMOVE:GIOCATORE
                    if(messages[1].equals(MapAdapter.getUsername()))
                        throw new Exception("You didn't move for too much time!");
                    game.logout(game.getPlayer(messages[1]));
                    break;
                case "DUEL"://DUEL:GIOCATORENEMICO
                    game.startDuel(messages[1]);
                    break;
                case "ENDDUEL":
                    game.endDuel();
                    break;
                case "SETBULLETS"://SETBULLETS:INT
                    game.setBullets(Integer.parseInt(messages[1]));
                    break;
                case "ADDBULLETS"://ADDBULLETS:INT
                    game.addBullets(Integer.parseInt(messages[1]));
                    break;
                default:
                    throw new Exception("Server sent weird command: " + messages[0]);
}