cursor.moveToFirst return FALSE at the second lap in the while loop

cursor.moveToFirst return FALSE at the second lap in the while loop. First line is inserted, instead when i insert another line, program don't work.Thanks This is my methods:

private void addDdtRow(String codiceMagazzino, String dataCreazione, String codiceLotto, Double quantita) { // TODO Auto-generated method stub boolean check = false; double qta = quantita; Cursor cursor = dbm.queryInventarioMag("CODICE_MAGAZZINO=?", new String[] { codiceMagazzino }); if (cursor != null) { int i_codMag = cursor.getColumnIndex(DatabaseStrings.CAMPO_COD_MAG); int i_riga = cursor.getColumnIndex(DatabaseStrings.CAMPO_RIGA); int i_dataCr = cursor .getColumnIndex(DatabaseStrings.CAMPO_DATA_CREAZIONE); int i_codLotto = cursor .getColumnIndex(DatabaseStrings.CAMPO_COD_LOTTO); int i_qta = cursor.getColumnIndex(DatabaseStrings.CAMPO_QTA);

        int i = 0;
        int pos = -1;
        boolean hasNext = cursor.moveToFirst();
        if (hasNext) {
            while (hasNext) {
                pos = cursor.getPosition();
                i = cursor.getInt(i_riga);
                if (cursor.getString(i_codMag).equals(codiceMagazzino)
                        && cursor.getString(i_codLotto).equals(codiceLotto)) {
                    check = true;
                    hasNext = false;
                } else {
                    indexRiga = i + 1;
                    hasNext = cursor.moveToNext();
                }
            }
            if (check) { // se match codLotto && match codArt
                cursor.moveToPosition(pos);
                indexRiga = i;
                qta = (qta + cursor.getInt(i_qta));
            }
        } else {
            indexRiga = 0;
        }

        if (check) {
            dbm.updateRigaMagaz(DatabaseStrings.TBL_MAGAZZINO, qta,
                    "CODICE_MAGAZZINO=? AND " + "RIGA=?", new String[] {
                            codiceMagazzino, String.valueOf(indexRiga) });
        } else {
            dbm.saveRigaMagaz(codiceMagazzino, indexRiga, dataCreazione,
                    codiceLotto, qta);
        }

    }
    displayList();
}

private void displayList() {
    // TODO Auto-generated method stub
    listaMagazzino = new LinkedList<LottiMagazzino>();
    listView = (ListView) findViewById(R.id.list_view_mag);
    Cursor cursor = dbm.queryInventarioMag("CODICE_MAGAZZINO=?",
            new String[] { codiceMagazzino });
    if (cursor != null) {
        int i_codMag = cursor.getColumnIndex(DatabaseStrings.CAMPO_COD_MAG);
        int i_riga = cursor.getColumnIndex(DatabaseStrings.CAMPO_RIGA);
        int i_dataCr = cursor
                .getColumnIndex(DatabaseStrings.CAMPO_DATA_CREAZIONE);
        int i_codLotto = cursor
                .getColumnIndex(DatabaseStrings.CAMPO_COD_LOTTO);
        int i_qta = cursor.getColumnIndex(DatabaseStrings.CAMPO_QTA);

        listaMagazzino.clear();
        boolean hasNext = cursor.moveToFirst();
        while (hasNext) {
            listaMagazzino.add(new LottiMagazzino(cursor
                    .getString(i_codMag), cursor.getInt(i_riga), cursor
                    .getString(i_dataCr), cursor.getString(i_codLotto),
                    cursor.getDouble(i_qta)));
            hasNext = cursor.moveToNext();
        }
    }
    adapter = new AdapterMagazzino(this, R.layout.row_listview,
            listaMagazzino);
    listView.setAdapter(adapter);
    listView.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
            final Dialog dialog = new Dialog(InventarioMag.this);
            dialog.setTitle("Dettaglio Riga DDT");
            dialog.setContentView(R.layout.dialog_view);
            listViewDialog = (ListView) dialog
                    .findViewById(R.id.listViewDialog);
            LottiMagazzino lm = adapter.getItem(position);

            listaInfo.clear();
            listaInfo.add(new LabelValue("Codice Magazzino", lm
                    .getCodiceMagazzino()));
            listaInfo.add(new LabelValue("Riga", lm.getRiga().toString()));
            listaInfo.add(new LabelValue("Data Creazione", lm
                    .getDataCreazione()));
            listaInfo.add(new LabelValue("Codice Lotto", lm
                    .getCodiceLotto()));
            listaInfo.add(new LabelValue("Quantità", lm.getQuantita()
                    .toString()));

            lbAdapter = new InfoAdapter(InventarioMag.this,
                    R.layout.row_info_lb, listaInfo);
            listViewDialog.setAdapter(lbAdapter);
            dialog.show();
        }
    });

}