Download pdf file from folder by using datagridview link label in C#

"Adobe reader coudln't read downloaed pdf file in C# datagridview cellcontent click":

  string Calibaration = gvCalibration.Rows[e.RowIndex].Cells["CalibrationCertificate"].Value.ToString();
string targetPath = System.Windows.Forms.Application.StartupPath + "\\App_Data\\CalibrationCertificate\\";
string Calfilename;
 Calfilename = Path.GetFileName(Calibaration);
 string extn = Path.GetExtension(Calibaration);
  var byteData = Encoding.UTF8.GetBytes(Calfilename);

using (SaveFileDialog sfd = new SaveFileDialog())
    {
 //Set Save dialog properties
  //sfd.Filter = "Text files (*.txt) | *.txt | All files(*.*) | *.* ";
 sfd.Filter = "Files (*" + extn + ")|*" + extn;
sfd.Title = "Save File as";
 sfd.CheckPathExists = true;
 sfd.RestoreDirectory = true;
  sfd.FileName = Calfilename;

 if (sfd.ShowDialog() != DialogResult.OK || string.IsNullOrEmpty(sfd.FileName))
                            {
                                return;
                            }

 using (var saveFileDialogStream = sfd.OpenFile())
                            {
  saveFileDialogStream.Write(byteData, 0, byteData.Length);
                            }