WebService (AsyncTask) only works with Debug?

I'm making my Android application load data from a WebService. In it, I'll load date data into a Spinner, and when it's complete, the same dates will load other types of data into a ListView, but for now I'm using an example to see how it got and already fix consistency errors.    Anyway, the problem is that when I do AsyncTask, I run it and should load Spinner, the app stops working . But when you put this part to debug the program can work perfectly .

Java code:

public class DownloadRules extends Options {

//OPÇÃO DO MENU
private final String NAMESPACE = "";
private final String URL = "";
private final String SOAP_ACTION = "";     //Tirei estes dados por segurança
private final String METHOD_NAME = "";
private String TAG = "";

private static String resultado;
private static String WSResultado;
public List<WSGetterSetter> listaLida;

Spinner spinner_baixarrota_datas;
Button button_baixarrota_selecionar;
TextView tv;
TextView tv2;

String dataSelecionada;

String[]exemplo = { "JAN", "FEB", "MAR", "APR", "MAY", "JUNE", "JULY", "AUG", "SEPT", "OCT", "NOV", "DEC" };
ListView listView_baixarrota_escolha;
ArrayAdapter arrayAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.baixar_rota1);

    spinner_baixarrota_datas = (Spinner) findViewById(R.id.spinner_baixarrota_datas);
    button_baixarrota_selecionar = (Button) findViewById(R.id.button_baixarrota_selecionar);
    tv = (TextView) findViewById(R.id.textView_baixarrota_resultData);
    listView_baixarrota_escolha = (ListView) findViewById(R.id.listView_baixarrota_escolha);
    tv2 = (TextView) findViewById(R.id.textView_baixarrota_result);

   // início debug
   AsyncCallWS task = new AsyncCallWS();
    task.execute();

    ArrayList<String> mylist = new ArrayList<String>();
    for (int i = 0; i < listaLida.size(); i++) mylist.add(i, listaLida.get(i).getsData());

    ArrayAdapter<String> spinner_datas = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, mylist);
    spinner_baixarrota_datas.setAdapter(spinner_datas);
    // fim debug

    // Layouts
    if(resultado == "**Registros Carregado"){
        button_baixarrota_selecionar.setEnabled(true);
        button_baixarrota_selecionar.setClickable(true);

        tv.setTextColor(Color.BLUE);

        arrayAdapter = new ArrayAdapter(this, android.R.layout.simple_expandable_list_item_1,exemplo);
        listView_baixarrota_escolha.setAdapter(arrayAdapter);
    }
    else {
        button_baixarrota_selecionar.setEnabled(false);
        button_baixarrota_selecionar.setClickable(false);

        tv2.setVisibility(View.VISIBLE);
    }
    //escolhendo a data
    spinner_baixarrota_datas.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
            dataSelecionada = spinner_baixarrota_datas.getSelectedItem().toString();
        }

        @Override
        public void onNothingSelected(AdapterView<?> parentView) {
        }

    });
    // escolhe o item do listView
    listView_baixarrota_escolha.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,
                                long id) {
            AlertDialog alerta;
            AlertDialog.Builder builder = new AlertDialog.Builder(BaixarRotas.this);
            builder.setTitle("Confirmar escolha:");
            builder.setMessage("-DATA: "+ dataSelecionada +"\n-ROTA: " + "\n-ATIVIDADE: " + "\n-RESPONSÁVEL: " + "\n-QUANTIDADE: ");

            builder.setPositiveButton("Sim", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface arg0, int arg1) {

                }
            });

            builder.setNegativeButton("Não", new DialogInterface.OnClickListener()
            { public void onClick(DialogInterface arg0, int arg1) {
                }
            });
            alerta = builder.create();
            alerta.show();
        }
    });

}
// Inutilizado, pois estou usando um exemplo logo embaixo (no AsyncTask)
public void getData() {
    SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME);

    PropertyInfo dataPI = new PropertyInfo();

    dataPI.setName("DATA");

    SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11);
    envelope.dotNet = true;
    envelope.setOutputSoapObject(request);

    AndroidHttpTransport androidHttpTransport = new AndroidHttpTransport(URL);
    try {
        androidHttpTransport.debug = true;
        androidHttpTransport.call(SOAP_ACTION, envelope);

        WSResultado = androidHttpTransport.responseDump;

        Log.i("t", "doInBackground");
    } catch (Exception e) {
        e.printStackTrace();
    }
}

private class AsyncCallWS extends AsyncTask<String, Void, Void> {
    @Override
    protected Void doInBackground(String... params) {
        Log.i(TAG, "doInBackground");
        // getData();
        // WSResultado é um exemplo de XML e está substituindo o getData(), um dado obtido pelo o WebService
        WSResultado = "<diffgr:diffgram xmlns:msdata=\"urn:schemas-microsoft-com:xml-msdata\" xmlns:diffgr=\"urn:schemas-microsoft-com:xml-diffgram-v1\">\n" +
                "               <NewDataSet xmlns=\"\">\n" +
                "                  <Table diffgr:id=\"Table2\" msdata:rowOrder=\"1\">\n" +
                "                     <DATA>2013-08-21T00:00:00-03:00</DATA>\n" +
                "                  </Table>\n" +
                "                  <Table diffgr:id=\"Table3\" msdata:rowOrder=\"2\">\n" +
                "                     <DATA>2013-08-22T00:00:00-03:00</DATA>\n" +
                "                  </Table>\n" +
                "               </NewDataSet>\n" +
                "            </diffgr:diffgram>";

        // CHAMADA parser (analisador do Xml)
        List<WSGetterSetter> datasR = null;
        InputStream is = new ByteArrayInputStream(WSResultado.getBytes());

        WSParser parser = new WSParser();
        datasR = parser.parse(is);

        listaLida = datasR;
        resultado = "**Registros Carregado";
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        Log.i(TAG, "onPostExecute");
        tv.setText(resultado);
    }

    @Override
    protected void onPreExecute() {
        Log.i(TAG, "onPreExecute");
        tv.setText("**Carregando...");
    }

    @Override
    protected void onProgressUpdate(Void... values) {
        Log.i(TAG, "onProgressUpdate");

    }

}

This part is where I have to put it to debug (especially in Spinner creation):

    AsyncCallWS task = new AsyncCallWS();
    task.execute();

    ArrayList<String> mylist = new ArrayList<String>();
    for (int i = 0; i < listaLida.size(); i++) mylist.add(i, listaLida.get(i).getsData());

    ArrayAdapter<String> spinner_datas = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, mylist);
    spinner_baixarrota_datas.setAdapter(spinner_datas);

The XML of this code if needed for better understanding:

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="81dp"
    android:layout_gravity="center_horizontal"
    android:layout_marginTop="7dp"
    android:layout_marginRight="7dp"
    android:layout_marginLeft="7dp">

    <TextView
        android:text="Data:"
        android:textSize="25dp"
        android:textStyle="bold"
        android:textColor="#ff010101"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/textView"
        android:layout_centerVertical="true"
        android:layout_alignParentStart="true" />

    <Spinner
        android:id="@+id/spinner_baixarrota_datas"
        android:layout_width="175dp"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"
        android:layout_alignStart="@+id/textView"
        android:layout_marginStart="64dp" />

    <Button
        style="?android:attr/buttonStyleSmall"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Selecionar"
        android:id="@+id/button_baixarrota_selecionar"
        android:layout_alignBottom="@+id/spinner_baixarrota_datas"
        android:layout_toEndOf="@+id/spinner_baixarrota_datas"
        android:clickable="false"
        android:enabled="false"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="**Registros não carregado"
        android:id="@+id/textView_baixarrota_resultData"
        android:textColor="#ffff0008"
        android:layout_alignParentTop="true"
        android:layout_alignStart="@+id/spinner_baixarrota_datas" />


</RelativeLayout>
<View
    android:layout_width="fill_parent"
    android:layout_height="2dp"
    android:background="#000"
    android:layout_below="@+id/spinner_baixarrota_datas"
    android:layout_alignParentStart="true" />

<FrameLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_gravity="center_horizontal">

    <TextView
        android:layout_width="334dp"
        android:layout_height="wrap_content"
        android:text="ROTA -  ATIVIDADE  -  RESPONSÁVEL  -  QUANTIDADE"
        android:id="@+id/tv_tabela"
        android:textColor="#000"
        android:layout_gravity="center_horizontal|top"
        android:layout_marginTop="15dp"
        android:background="#f0b4b9b7"/>

    <ListView
        android:layout_width="334dp"
        android:layout_height="356dp"
        android:id="@+id/listView_baixarrota_escolha"
        android:layout_gravity="center"
        android:divider="#FFCC00"
        android:dividerHeight="2dp"
        android:layout_weight="1"
        android:background="@drawable/borda"/>

    <TextView
        android:layout_width="334dp"
        android:layout_height="356dp"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="**Registros não carregado"
        android:id="@+id/textView_baixarrota_result"
        android:layout_gravity="center"
        android:textColor="#ffff0008"
        android:background="@drawable/borda"
        android:textAlignment="center"
        android:visibility="invisible"/>

</FrameLayout>

Logcat displays the following error: "Attempt to invoke interface method 'int java.util.List.size ()' on a null object reference" I've seen other questions, but none were effective. So does anyone have any idea what this problem is? Thankful.