c＃中的excel文件格式不正确

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using Microsoft.Office.Interop.Excel;

namespace MMC_TA_TOOL
{
  public  class ExpotExcel
    {
        public  void ExportToExcel(DataSet dataSet, string outputPath)
        {
            // Create the Excel Application object
            Application excelApp = new Application();

            // Create a new Excel Workbook
            Workbook excelWorkbook = excelApp.Workbooks.Add(Type.Missing);

            int sheetIndex = 0;

            // Copy each DataTable
            foreach (System.Data.DataTable dt in dataSet.Tables)
            {

                // Copy the DataTable to an object array
                object[,] rawData = new object[dt.Rows.Count + 1, dt.Columns.Count];

                // Copy the column names to the first row of the object array
                for (int col = 0; col < dt.Columns.Count; col++)
                {
                    rawData[0, col] = dt.Columns[col].ColumnName;
                }

                // Copy the values to the object array
                for (int col = 0; col < dt.Columns.Count; col++)
                {
                    for (int row = 0; row < dt.Rows.Count; row++)
                    {
                        rawData[row + 1, col] = dt.Rows[row].ItemArray[col];
                    }
                }

                // Calculate the final column letter
                string finalColLetter = string.Empty;
                string colCharset = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
                int colCharsetLen = colCharset.Length;

                if (dt.Columns.Count > colCharsetLen)
                {
                    finalColLetter = colCharset.Substring(
                        (dt.Columns.Count - 1) / colCharsetLen - 1, 1);
                }

                finalColLetter += colCharset.Substring(
                        (dt.Columns.Count - 1) % colCharsetLen, 1);

                // Create a new Sheet
                Worksheet excelSheet = (Worksheet)excelWorkbook.Sheets.Add(
                    excelWorkbook.Sheets.get_Item(++sheetIndex),
                    Type.Missing, 1, XlSheetType.xlWorksheet);

                excelSheet.Name = dt.TableName;

                // Fast data export to Excel
                string excelRange = string.Format("A1:{0}{1}",
                    finalColLetter, dt.Rows.Count + 1);

                excelSheet.get_Range(excelRange, Type.Missing).Value2 = rawData;

                // Mark the first row as BOLD
                ((Range)excelSheet.Rows[1, Type.Missing]).Font.Bold = true;
            }

            // Save and Close the Workbook
            excelWorkbook.SaveAs(outputPath, XlFileFormat.xlWorkbookNormal, Type.Missing,
                Type.Missing, Type.Missing, Type.Missing, XlSaveAsAccessMode.xlExclusive,
                Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
          //  excelWorkbook.SaveAs(Type.Missing, XlFileFormat.xlWorkbookNormal, System.Reflection.Missing.Value, System.Reflection.Missing.Value, false, false, XlSaveAsAccessMode.xlShared, false, false, System.Reflection.Missing.Value, System.Reflection.Missing.Value, System.Reflection.Missing.Value);

            excelWorkbook.Close(true, Type.Missing, Type.Missing);
            excelWorkbook = null;
					

            // Release the Application object
            excelApp.Quit();
            excelApp = null;

            // Collect the unreferenced objects
            GC.Collect();
            GC.WaitForPendingFinalizers();

        }
    }
}

i使用上面的代码来加载我的数据设置为excel但是在创建之后，当我试图打开时，除了它正在抛出文件格式不正确之后请帮助我。

i am using above code to load my data set to excel but after creation when i am trying to open that exce it is throwing that file format is not correct plase help me on this.