How to save the WinForms GridControl with changed values to an excel sheet?

private void btnExport_Click(object sender, EventArgs e)
{
   ExcelEngine engine = new ExcelEngine();
   IApplication app = engine.Excel.Application;
   app.DefaultVersion = ExcelVersion.Excel2010;
   IWorkbook workBook = app.Workbooks.Create();
   workBook = engine.Excel.Workbooks.Open(@"..\..\Book1.xlsx");
   IWorksheet sheet = workBook.Worksheets[0];
   control.GridToExcel(this.gridControl1, sheet, ConverterOptions.Default);

   //Save the workbook.
   workBook.Save();
   Process.Start(@"..\..\Book1.xlsx");
}

Private Sub btnExport_Click(ByVal sender As Object, ByVal e As EventArgs)
   Dim engine As New ExcelEngine()
   Dim app As IApplication = engine.Excel.Application
   app.DefaultVersion = ExcelVersion.Excel2010
   Dim workBook As IWorkbook = app.Workbooks.Create()
   workBook = engine.Excel.Workbooks.Open("..\..\Book1.xlsx")
   Dim sheet As IWorksheet = workBook.Worksheets(0)
   control.GridToExcel(Me.gridControl1, sheet, ConverterOptions.Default)

   'Save the workbook.
   workBook.Save()
   Process.Start("..\..\Book1.xlsx")
End Sub