public Form1()
{
    InitializeComponent();
    DataTable data = new DataTable();
    data.Columns.Add();
    data.Rows.Add(\"val1\");
    flyGrid1.Rows.DataSource = data;
}

private int VM_GetCount(NodeBase sender)
        {
            if (sender is VirtualRootNode)
            {
                try
                {
                    return DataTableProvider.Instance.GetDataTable().Rows.Count;
                }
                catch(Exception ex)
                {
                    Siemens.Diagnostics.Trace.WriteLine(\"Error while trying to get count for datatable: \" + ex, \"JournalView\");
                }
            }

            if (sender.Parent is VirtualRootNode)
            {
                try
                {
                    return DataTableProvider.Instance.GetPeriodTableByIndex(sender.Index).Rows.Count;
                }
                catch (Exception ex)
                {
                    Siemens.Diagnostics.Trace.WriteLine(\"Error while trying to get count for datetable: \" + ex, \"JournalView\");
                }
            }

            return 0;
        }