Problem with AlertDialog and multichoice

I have an AlertDialog that has a multichoice and that it is filled by means of an arraylist of objects, that data I get from a webservices.

The problem I have with this AlertDialog is that when I click on my actionbar to see if it loads the correct data, but when I try to tap the check I need, I do not select anything and I close the alertDialog and he does not send me an error in the logcat.

I clarify the AlertDialog I believe in the OnpostExecute since I am using Asyntask

I leave code

Class Asyntask, where I generate my alertDialog

private class AsyncZona extends AsyncTask<String, ArrayList, ArrayList>
    {
        private String ONControlWSURL;
        public AsyncZona(String ONControlWSURL)
        {
            this.ONControlWSURL = ONControlWSURL;
        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();

        }

        @Override
        protected ArrayList doInBackground(String... params) {
            ZonaArrayList = new ArrayList<Zona>();
            webService O_WS = new webService(ONControlWSURL);
            ZonaArrayList=O_WS.Zona();
            return null;
        }

        @Override
        protected void onPostExecute(ArrayList arrayList){
            super.onPostExecute(arrayList);


            final String[] zona = new String[ZonaArrayList.size()];
            //zona = ZonaArrayList.toArray(zona);
            for(int i=0; i<ZonaArrayList.size(); i++){
                //Obtiene el campo Descripción y lo agrega al array de strings "zona".
                zona[i] = ZonaArrayList.get(i).getDescripcion();
                // zona[i] = ZonaArrayList.get(i).getClave();
            }
             final boolean[] isSelectedArray ={false,false,false,false,false,false};
                AlertDialog.Builder builder = new AlertDialog.Builder(Clientes.this);
                builder.setTitle("Selecciona la Zona(s) que Visitaras");
                builder.setMultiChoiceItems(zona, isSelectedArray, new DialogInterface.OnMultiChoiceClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which, boolean isChecked) {

                        if (isChecked)
                        {
                            Toast.makeText(getApplicationContext(),"Seleccionado" + zona[which],Toast.LENGTH_SHORT).show();
                        }
                    }
                });
                builder.setAdapter(adapter, new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int item) {

                    }
                });
                builder.setPositiveButton("Aceptar", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        //do something
                    }
                });;
                builder.setNegativeButton("Cancelar", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.cancel();
                    }
                });

                AlertDialog alert = builder.create();
                alert.show();
        }
    }

Solution I leave the code

 @Override
        protected void onPostExecute(ArrayList arrayList){
            super.onPostExecute(arrayList);

            final String[] zona = new String[ZonaArrayList.size()];
            // zona = ZonaArrayList.toArray(zona);
            for(int i=0; i<ZonaArrayList.size(); i++){
                //Obtiene el campo Descripción y lo agrega al array de strings "zona".
                zona[i] = ZonaArrayList.get(i).getDescripcion();
                // zona[i] = ZonaArrayList.get(i).getClave();
            }
            final boolean[] selCrayons={true,false,true};
            AlertDialog.Builder dialog=new AlertDialog.Builder(Clientes.this);
            dialog.setTitle("Selecciona la(s) Zonas a Visitar");
            dialog.setMultiChoiceItems(zona,selCrayons,new DialogInterface.OnMultiChoiceClickListener() {
                @Override
                public void onClick(DialogInterface arg0, int arg1, boolean arg2) {
                    // TODO Auto-generated method stub
                    if(arg2) {
                        Toast.makeText(getApplicationContext(), "Zona Seleccionada " + zona[arg1],Toast.LENGTH_SHORT).show();
                    }
                }
            });
            dialog.setPositiveButton("Ok",new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    // TODO Auto-generated method stub
                }
            });
            dialog.setNegativeButton("Cancelar", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.cancel();
                }
            });
            AlertDialog alertDialog=dialog.create();
            alertDialog.show();
        }
    }