Devexpress gridview export customised header

using DevExpress.XtraPrinting;
using DevExpress.Printing.ExportHelpers;
using DevExpress.Export;

private void simpleButton1_Click(object sender, EventArgs e) {
    // Ensure that the data-aware export mode is enabled.
    DevExpress.Export.ExportSettings.DefaultExportType = ExportType.DataAware;           
    // Create a new object defining how a document is exported to the XLSX format.
    XlsxExportOptionsEx options = new XlsxExportOptionsEx();
    // Subscribe to the CustomizeSheetHeader event. 
    options.CustomizeSheetHeader += options_CustomizeSheetHeader;
    // Export the grid data to the XLSX format.
    string file = "grid-export.xlsx";
    gridControl.ExportToXlsx(file, options);
    // Open the created document.
    System.Diagnostics.Process.Start(file);           
}

void options_CustomizeSheetHeader(DevExpress.Export.ContextEventArgs e) {
    // Create a new row.
    CellObject row = new CellObject();
    // Specify row values.
    row.Value = "The document is exported from the IssueList database.";
    // Specify row formatting.
    XlFormattingObject rowFormatting = new XlFormattingObject();
    rowFormatting.Font = new XlCellFont { Bold = true, Size = 14 };
    rowFormatting.Alignment = new DevExpress.Export.Xl.XlCellAlignment { HorizontalAlignment = DevExpress.Export.Xl.XlHorizontalAlignment.Center, VerticalAlignment = DevExpress.Export.Xl.XlVerticalAlignment.Top };
    row.Formatting = rowFormatting;
    // Add the created row to the output document.
    e.ExportContext.AddRow(new [] {row});
    // Add an empty row to the output document.
    e.ExportContext.AddRow();
    // Merge cells of two new rows. 
    e.ExportContext.MergeCells(new DevExpress.Export.Xl.XlCellRange(new DevExpress.Export.Xl.XlCellPosition(0, 0), new DevExpress.Export.Xl.XlCellPosition(5, 1)));
}