Launch excel file using Process object

I am getting error trying to launch the specified executable is not a valid application for this os platform , I am trying to launch a Template.XLS file save values in the files then close file. once i close file I the process detects that the file is close  and then i go do something, can someone assist me.

      using (StatusBusy busy = new StatusBusy("Launching template.xls. Please wait patiently..."))
                {



                    if (File.Exists(fileName))
                    {
                        Process process = new Process();

                        process.EnableRaisingEvents = true;
                        process.Exited += new EventHandler(process_Exited);

                        process.StartInfo.UseShellExecute = false;
                        process.StartInfo.FileName = fileName;
                        process.WaitForExit();

                        if (process.ExitCode == 0)
                        {

                            MessageBox.Show("template.xlsprocess complete.");

                            return true;
                        }
                        else
                        {
                            MessageBox.Show(" template.xls process Failed.");
                            process.Kill();
                            return false;
                        }
                    }
                    else
                    {
                        MessageBox.Show("File does not exist");
                        return false;
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error occurred launching SN template. ",ex.Message);
                return false;
            }