我的秒表没有计时和显示时间

我在C#中编写了一个程序，假设它计算在RSA中加密和解密所需的时间，然后显示时间。我将秒表对象放入加密和解密方法中，而不是创建自己的方法。无论我尝试过什么，输出总是00:00:00:00。

public void EncryptFile(string inFile)
{
   Stopwatch stopWatch = new Stopwatch();
   // Get the elapsed time as a TimeSpan value.
   TimeSpan ts = stopWatch.Elapsed;
   stopWatch.Start();
   // Create instance of Rijndael for 
   // symetric encryption of the data.
   RijndaelManaged rjndl = new RijndaelManaged();
   rjndl.KeySize = 256;
   rjndl.BlockSize = 256;
   rjndl.Mode = CipherMode.CBC;
   ICryptoTransform transform = rjndl.CreateEncryptor();
   // Use RSACryptoServiceProvider to 
   // enrypt the Rijndael key. 
   // rsa is previously instantiated:  
   // rsa = new RSACryptoServiceProvider(cspp); 
   byte[] keyEncrypted = rsa.Encrypt(rjndl.Key, false);
   // Create byte arrays to contain 
   // the length values of the key and IV. 
   byte[] LenK = new byte[4];
   byte[] LenIV = new byte[4];
   int lKey = keyEncrypted.Length;
   LenK = BitConverter.GetBytes(lKey);
   int lIV = rjndl.IV.Length;
   LenIV = BitConverter.GetBytes(lIV);
   // Write the following to the FileStream 
   // for the encrypted file (outFs): 
   // - length of the key 
   // - length of the IV 
   // - ecrypted key 
   // - the IV 
   // - the encrypted cipher content 
   int startFileName = inFile.LastIndexOf("''") + 1;
   // Change the file's extension to ".enc" 
   string outFile = EncrFolder +
      inFile.Substring(startFileName,
      inFile.LastIndexOf(".") -      startFileName) + ".enc";
   using (FileStream outFs = new FileStream(outFile, FileMode.Create))
   {
      outFs.Write(LenK, 0, 4);
      outFs.Write(LenIV, 0, 4);
      outFs.Write(keyEncrypted, 0, lKey);
      outFs.Write(rjndl.IV, 0, lIV);
      // Now write the cipher text using 
      // a CryptoStream for encrypting. 
      using (CryptoStream outStreamEncrypted =
         new CryptoStream(outFs, transform, CryptoStreamMode.Write))
      {
         int count = 0;
         int offset = 0;
         // blockSizeBytes can be any arbitrary size. 
         int blockSizeBytes = rjndl.BlockSize / 8;
         byte[] data = new byte[blockSizeBytes];
         int bytesRead = 0;
         using (FileStream inFs = new FileStream(inFile, FileMode.Open))
         {
            do
            {
               count = inFs.Read(data, 0, blockSizeBytes);
               offset += count;
               outStreamEncrypted.Write(data, 0, count);
               bytesRead += blockSizeBytes;
            } while (count > 0);
            inFs.Close();
         }
         outStreamEncrypted.FlushFinalBlock();
         stopWatch.Stop();
         // Format and display the TimeSpan value. 
         string elapsedTime = string.Format("{0:00}:{1:00}:{2:00}.{3:00}",
            ts.Hours, ts.Minutes, ts.Seconds, ts.Milliseconds / 10);
         label3.Text = "Elapsed time " + elapsedTime;
         outStreamEncrypted.Close();
      }
      outFs.Close();
   }
}