Как можно сделать на три колонки один Header.

Sorrrrrry! Я хотел сказать для трёх колонок один Header.
:-)

Aspx
<asp:GridView ID="gv" OnRowCreated="gv_RowCreated"      runat="server"  AutoGenerateColumns="false">
Code C#
protected void gv_RowCreated(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.Header)
        {
            TableCell oCell;
            e.Row.Cells.Clear();           
           
            oCell = new TableCell();
            oCell.Text = "Room";
            e.Row.Cells.Add(oCell);
            oCell = new TableCell();
            oCell.Text = "Prof";
            oCell.ColumnSpan = 3;
            e.Row.Cells.Add(oCell);
            oCell = new TableCell();
            oCell.Text = "Categ.";           
            e.Row.Cells.Add(oCell);
            oCell = new TableCell();
            oCell.Text = "Adult price & Quanttity";
            oCell.ColumnSpan = 9;
            e.Row.Cells.Add(oCell);
            oCell = new TableCell();
            oCell.Text = "Child price & Quanttity";
            oCell.ColumnSpan = 15;
            e.Row.Cells.Add(oCell);
        }
    }