Open XML Excel-Zelle Formatierung

Ich versuche zu exportieren, in excel mithilfe von Open XML mit einfachen Formatierung. Export nach Excel funktioniert. Das problem mit der Formatierung der Daten. Ich versuche, sehr grundlegende Formatierungen. d.h. die Spaltennamen sollten in Fett und der rest der Inhalt in normaler Schrift. Dies ist, was ich getan habe. Bitte lassen Sie mich wissen, wo mache ich falsch.

private Stylesheet GenerateStyleSheet()
{
    return new Stylesheet(
        new Fonts(
            new Font(new DocumentFormat.OpenXml.Spreadsheet.FontSize { Val = 12},
                new Bold(),
            new Font(new DocumentFormat.OpenXml.Spreadsheet.FontSize { Val = 12}))
        )
    );
}
 protected void ExportExcel(DataTable dtExport)
    {
        Response.ClearHeaders();
        Response.ClearContent();
        Response.Clear();
        Response.Buffer = true;
        Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml";
        //"application/vnd.openxmlformats-officedocument.spreadsheetml.worksheet+xml" '"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" '"application/vnd.ms-excel"
        Response.AddHeader("content-disposition", "attachment; filename=Test.xlsx");
        Response.Charset = "";
        this.EnableViewState = false;
        MemoryStream ms = new MemoryStream();
        SpreadsheetDocument objSpreadsheet = SpreadsheetDocument.Create(ms, SpreadsheetDocumentType.Workbook);
        WorkbookPart objWorkbookPart = objSpreadsheet.AddWorkbookPart();
        objWorkbookPart.Workbook = new Workbook();
        WorksheetPart objSheetPart = objWorkbookPart.AddNewPart<WorksheetPart>();
        objSheetPart.Worksheet = new Worksheet(new SheetData());
        Sheets objSheets = objSpreadsheet.WorkbookPart.Workbook.AppendChild<Sheets>(new Sheets());
        Sheet objSheet = new Sheet();
        objSheet.Id = objSpreadsheet.WorkbookPart.GetIdOfPart(objSheetPart);
        objSheet.SheetId = 1;
        objSheet.Name = "mySheet";
        objSheets.Append(objSheet);

        WorkbookStylesPart stylesPart = objSpreadsheet.WorkbookPart.AddNewPart<WorkbookStylesPart>();
        stylesPart.Stylesheet = GenerateStyleSheet();
        stylesPart.Stylesheet.Save();
        objSheetPart.Worksheet.Save();

        objSpreadsheet.WorkbookPart.Workbook.Save();
        for (int cols = 0; cols < dtExport.Columns.Count; cols++)
        {
            Cell objCell = InsertCellInWorksheet(GetColumnName(cols), 1, objSheetPart);
            objCell.CellValue = new CellValue(dtExport.Columns[cols].ColumnName);
            objCell.DataType = new EnumValue<CellValues>(CellValues.String);
            objCell.StyleIndex = 0;
        }
        objSheetPart.Worksheet.Save();
        objSpreadsheet.WorkbookPart.Workbook.Save();
        for (uint row = 0; row < dtExport.Rows.Count; row++)
        {
            for (int cols = 0; cols < dtExport.Columns.Count; cols++)
            {
                //row + 2 as we need to start adding data from second row. First row is left for header
                Cell objCell = InsertCellInWorksheet(GetColumnName(cols), row + 2, objSheetPart);
                objCell.CellValue = new CellValue(Convert.ToString(dtExport.Rows[Convert.ToInt32(row)][cols]));
                objCell.DataType = new EnumValue<CellValues>(CellValues.String);
                objCell.StyleIndex = 1;
            }
        }
        objSheetPart.Worksheet.Save();
        objSpreadsheet.WorkbookPart.Workbook.Save();
        objSpreadsheet.Close();
        ms.WriteTo(Response.OutputStream);
        Response.Flush();
        Response.End();

    }
 //Given a column name, a row index, and a WorksheetPart, inserts a cell into the worksheet. 
    //If the cell already exists, return it. 
    private Cell InsertCellInWorksheet(string columnName, uint rowIndex, WorksheetPart worksheetPart)
    {
        Worksheet worksheet = worksheetPart.Worksheet;
        SheetData sheetData = worksheet.GetFirstChild<SheetData>();
        string cellReference = (columnName + rowIndex.ToString());

        //If the worksheet does not contain a row with the specified row index, insert one. 
        Row row = default(Row);

        if ((sheetData.Elements<Row>().Where(r => r.RowIndex.Value == rowIndex).Count() != 0))
        {
            row = sheetData.Elements<Row>().Where(r => r.RowIndex.Value == rowIndex).First();
        }
        else
        {
            row = new Row();
            row.RowIndex = rowIndex;
            sheetData.Append(row);
        }

        //If there is not a cell with the specified column name, insert one. 
        if ((row.Elements<Cell>().Where(c => c.CellReference.Value == columnName + rowIndex.ToString()).Count() > 0))
        {
            return row.Elements<Cell>().Where(c => c.CellReference.Value == cellReference).First();
        }
        else
        {
            //Cells must be in sequential order according to CellReference. Determine where to insert the new cell. 
            Cell refCell = null;
            foreach (Cell cell in row.Elements<Cell>())
            {
                if ((string.Compare(cell.CellReference.Value, cellReference, true) > 0))
                {
                    refCell = cell;
                    break; //TODO: might not be correct. Was : Exit For
                }
            }
            Cell newCell = new Cell();
            newCell.CellReference = cellReference;

            row.InsertBefore(newCell, refCell);
            return newCell;
        }

    }