Excel file not created as expected

                        string Path0="c:\\dp2\\Ex0.xlsx";
                        CreateSpreadsheetWorkbook3(Path0);

        public static void CreateSpreadsheetWorkbook3(string filepath)
        {
            // Create a spreadsheet document by supplying the filepath.
            // By default, AutoSave = true, Editable = true, and Type = xlsx.
            SpreadsheetDocument spreadsheetDocument = SpreadsheetDocument.
                Create(filepath, SpreadsheetDocumentType.Workbook);

            // Add a WorkbookPart to the document.
            WorkbookPart workbookpart = spreadsheetDocument.AddWorkbookPart();
            workbookpart.Workbook = new DocumentFormat.OpenXml.Spreadsheet.Workbook();

            // Add a WorksheetPart to the WorkbookPart.
            WorksheetPart worksheetPart = workbookpart.AddNewPart<WorksheetPart>();
            worksheetPart.Worksheet = new DocumentFormat.OpenXml.Spreadsheet.Worksheet(new SheetData());

            // Add Sheets to the Workbook.
            DocumentFormat.OpenXml.Spreadsheet.Sheets sheets = spreadsheetDocument.WorkbookPart.Workbook.
                AppendChild<DocumentFormat.OpenXml.Spreadsheet.Sheets>(new DocumentFormat.OpenXml.Spreadsheet.Sheets());

            // Append a new worksheet and associate it with the workbook.
            Sheet sheet = new Sheet()
            {
                Id = spreadsheetDocument.WorkbookPart.
                    GetIdOfPart(worksheetPart),
                SheetId = 1,
                Name = "mySheet"
            };
            sheets.Append(sheet);

            workbookpart.Workbook.Save();

            // Close the document.
            spreadsheetDocument.Close();
        }

Many Thanks & Best Regards, Hua Min