Ouvrir et enregistrer le document excel en c#

Je suis en train d'ouvrir et enregistrer un document Excel en C# mais je reçois toujours un message d'erreur: "un objet COM qui a été séparé de son RCW sous-jacent ne peut pas être utilisé." à la ligne ExcelApp.Quit(); j'ai googlé beaucoup de solutions mais aucune ne fonctionne pour moi jusqu'à présent.

Voici mon code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using Microsoft.Office.Core;
using Excel = Microsoft.Office.Interop.Excel;
namespace test_excel
{
public partial class Form1 : Form
{
Excel.Application ExcelApp = null;
Excel.Workbook ExcelWorkBook = null;
Excel.Sheets ExcelSheets = null;
Excel.Worksheet MySheet = null;
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
ExcelApp = new Excel.Application();
ExcelApp.Visible = false;
ExcelWorkBook = ExcelApp.Workbooks.Open("c:\\test.xls", 0, true, 5, "", "", false, Excel.XlPlatform.xlWindows, "", true, false, 0, true, false, false);
ExcelSheets = ExcelWorkBook.Worksheets;
MySheet = (Excel.Worksheet)ExcelSheets.get_Item("Sheet1");
int a = (int)MySheet.Range["a1"].Value2;
label1.Visible = true;
int b = a + 1;
label1.Text = a.ToString() + " | " + b.ToString();
MySheet.Range["a1"].Value2 = b;
}
private void releaseObject(object obj)
{
try
{
System.Runtime.InteropServices.Marshal.ReleaseComObject(obj);
obj = null;
}
catch (Exception ex)
{
obj = null;
MessageBox.Show("Unable to release the Object " + ex.ToString());
}
finally
{
GC.Collect();
}
}
private void button2_Click(object sender, EventArgs e)
{
try
{
System.Runtime.InteropServices.Marshal.ReleaseComObject(ExcelSheets);
ExcelWorkBook.Close(false, System.Reflection.Missing.Value, System.Reflection.Missing.Value);
releaseObject(ExcelApp);
releaseObject(ExcelSheets);
releaseObject(ExcelWorkBook);
ExcelApp.Visible = false;
ExcelApp.UserControl = false;
ExcelWorkBook.SaveAs("c:\\test.xls", Excel.XlFileFormat.xlWorkbookNormal,
null, null, false, false, Excel.XlSaveAsAccessMode.xlShared,
false, false, null, null, null);
ExcelWorkBook.Close();
}
catch (Exception err)
{
String msg;
msg = "Error: ";
msg = String.Concat(msg, err.Message);
msg = String.Concat(msg, " Line: ");
msg = String.Concat(msg, err.Source);
Console.WriteLine(msg);
}
finally
{
try
{
ExcelApp.Visible = false;
ExcelApp.UserControl = false;
ExcelWorkBook.Close(true, null, null);
ExcelApp.Workbooks.Close();
}
catch { }
ExcelApp.Quit();
if (MySheet != null) { System.Runtime.InteropServices.Marshal.ReleaseComObject(MySheet); }
if (ExcelWorkBook != null) { System.Runtime.InteropServices.Marshal.ReleaseComObject(ExcelWorkBook); }
if (ExcelApp != null) { System.Runtime.InteropServices.Marshal.ReleaseComObject(ExcelApp); }
MySheet = null;
ExcelWorkBook = null;
ExcelApp = null;
GC.Collect();
}
} 
}
}