table multi level header not show labels

[dxq38]

I added a multi level header like this:

The multi header is ok when program start up, but when i add another one, it should be "channel 17", it's not show all the labels. The code like this:

int icols = table->columnCount();
    for (int i = 0; i < 5; ++i)
    {
        table->insertColumn(icols + i);
    }
    hHeader->model()->insertColumns(icols, 5);
    hHeader->setSpan(0, icols, 1, 5);

    hHeader->setCellLabel(0, icols, "channel " + QString::number((icols - 2) / 5 + 1));
    hHeader->setCellLabel(1, icols, "A");
    hHeader->setCellLabel(1, icols + 1, "f");
    hHeader->setCellLabel(1, icols + 2, "Ø");
    hHeader->setCellLabel(1, icols + 3, "t1");
    hHeader->setCellLabel(1, icols + 4, "t2");

void GridTableHeaderView::setCellLabel(int row, int column,
                                       const QString &label) {
//    qDebug() << "set row=" << row << "set col=" << column;
  QModelIndex index =model()->index(row, column);
  model()->setData(index, label, Qt::DisplayRole);
}

bool GridTableHeaderModel::setData(const QModelIndex &index,
                                   const QVariant &value, int role) {
  if (index.isValid()) {
//      qDebug() << "index row=" << index.row() << "col=" << index.column();
    TableHeaderItem *item =
        static_cast<TableHeaderItem *>(index.internalPointer());
    if (role == ColumnSpanRole) {
      int col = index.column();
      int span = value.toInt();
      if (span > 0) {
        if (col + span - 1 >= _column)
          span = _column - col;
        item->setData(span, ColumnSpanRole);
      }
    } else if (role == RowSpanRole) {
      int row = index.row();
      int span = value.toInt();
      if (span > 0) {
        if (row + span - 1 > _row)
          span = _column - row;
        item->setData(span, RowSpanRole);
      }
    } else
      item->setData(value, role);
    return true;
  }
  return false;
}

void TableHeaderItem::setData(const QVariant &data, int role) {
    qDebug() << "role=" << role << "data=" << data;
  m_itemData.insert(role, data);
}

class TableHeaderItem {
public:
  TableHeaderItem(TableHeaderItem *parent = 0);
  TableHeaderItem(int row, int column, TableHeaderItem *parent = 0);

  TableHeaderItem *insertChild(int row, int col);
  TableHeaderItem *child(int row, int col);

  TableHeaderItem *parent();

  int row() const;
  int column() const;

  void setData(const QVariant &data, int role);
  QVariant data(int role) const;

  void clear();

  bool removeColumns(int position, int columns);
  bool insertColumns(int position, int columns);

private:
  TableHeaderItem *m_parentItem;
  int _row;
  int _column;

  QHash<QPair<int, int>, TableHeaderItem *> m_childItems;
  QHash<int, QVariant> m_itemData;
};