Работа с ActiveQt, сохранение изменений ячеек Exel документа Опции

[aqt]

Здравствуйте!
Подскажите пожалуйста, как сохранить изменения в Exel документе. Создал такой класс:

class MyTableWidget : public QTableWidget
{
    Q_OBJECT

public:

    QTableWidgetItem *my_item;

    QAxObject *excel;
    QAxObject *workbooks;
    QAxObject *workbook;
    QAxObject *sheets;
    QAxObject *sheet;
    QAxObject *cell;
    QAxObject *row;

MyTableWidget()
    {
        excel = new QAxObject("Excel.Application", this );

        excel->dynamicCall("SetVisible(bool)", FALSE );

        workbooks = excel->querySubObject("WorkBooks()");

        workbooks->dynamicCall("Open (const QString&)", QString("C:/data1.xls"));

        workbook = excel->querySubObject("ActiveWorkBook");

        if (workbook) {
            sheets = workbook->querySubObject("Sheets");
            sheet = sheets->querySubObject("Item(1)");
            sheet->dynamicCall("Select()");

            connect(excel,     SIGNAL(exception(int, QString, QString, QString)), SLOT(MYdebugError(int,QString,QString,QString)));
            connect(workbooks, SIGNAL(exception(int, QString, QString, QString)), SLOT(MYdebugError(int,QString,QString,QString)));
            connect(workbook,  SIGNAL(exception(int, QString, QString, QString)), SLOT(MYdebugError(int,QString,QString,QString)));
            connect(sheets,    SIGNAL(exception(int, QString, QString, QString)), SLOT(MYdebugError(int,QString,QString,QString)));
            connect(sheet,     SIGNAL(exception(int, QString, QString, QString)), SLOT(MYdebugError(int,QString,QString,QString)));

            int r = 0;
            setColumnCount(4);
            setRowCount(0);
            QString v = "";

            while(r >= 0)
            {
                for (int c=0; c<4 && r>=0; ++c)
                {
                    cell = sheet->querySubObject("cells(int, int)", r+1, c+1 );
                    cell->dynamicCall("Select()");

                    if (cell) v = cell->property("Value").toString();
                    else v = "";

                    qDebug() << r << c << v;

                    if (c == 0 && r > 0)
                    {
                        if (v.length() != 0 && r < 10000)
                        {
                            insertRow(rowCount());
                            row = sheet->querySubObject("rows(int)", r+1 );
                            int points = row->property("Height").toInt();
                            int pixels = points * 1.2;
                            setRowHeight(r-1, pixels);
                        }
                        else r = -11111;
                    }
                    if (r >= 0)
                    {
                        my_item = new QTableWidgetItem(v);
                        if (r == 0)setHorizontalHeaderItem(c, my_item);
                        else setItem(r-1, c, my_item);
                    }
                }
                r++;
            }
        }

        delete row;

        connect(this, SIGNAL(itemChanged (QTableWidgetItem *)), SLOT (slot_itemChanged(QTableWidgetItem *)));
    }

    ~MyTableWidget()
    {
        delete excel;
        delete workbooks;
        delete workbook;
        delete sheets;
        delete sheet;
        delete cell;
    }

public slots:


    void MYdebugError(int errorCode, QString source, QString description, QString help)
    {
        qDebug() << errorCode << source << description << help;
    }

    void slot_itemChanged ( QTableWidgetItem * item )
    {
        cell = sheet->querySubObject("cells(int, int)",  item->row()+2, item->column()+1  );

        cell->dynamicCall("Select()");
        cell->setProperty("Value", item->text());
        workbook->dynamicCall("Save(void)");
    }
};

необходимо, чтобы в слоте slot_itemChanged значение ячейки менялось. Сейчас вместо этого появляется окно с сообщением: "Файл "..." уже существует. ..."