Error in Decryption --> Invalid padding and Data size is not block size multiple

HI All,
please find below code for those two errors.


FileStream fSource;
FileStream fDestination;
ICryptoTransform dec;
Byte[] inputChar = null;
Byte[] decryptedChar = null;
//Int64 bfrSize = 9999999;
int count;
int decryptedCount;
int dataSize = 150000;

string sourcePath = ConfigurationSettings.AppSettings["EncryptedBackUpFilesPath"] + fileName;
string destinationPath = ConfigurationSettings.AppSettings["DecryptedFiles"] + fileName;
fSource = File.OpenRead(sourcePath);
fDestination = File.Create(destinationPath);
inputChar = new Byte[dataSize + 16];
decryptedChar = new Byte[dataSize + 16];

dec = nKey.CreateDecryptor();

try
{
count = fSource.Read(inputChar, 0, dataSize);
while (count > 0)
{
decryptedCount = dec.TransformBlock(inputChar, 0, count, decryptedChar, 0);
fDestination.Write(decryptedChar, 0, decryptedCount);
count = fSource.Read(inputChar, 0, dataSize);
fDestination.Write(decryptedChar, 0, decryptedCount);
AesManaged aes = new AesManaged();
// aes.Padding = PaddingMode.None;
}
decryptedChar = dec.TransformFinalBlock(inputChar, 0, count);//Error getting here

fDestination.Write(decryptedChar, 0, decryptedChar.Length);
Logger.LogError(destinationPath + " is decrypted. POMID is --> " + pomId);

//CryptoStream crStream = new CryptoStream(fDestination, nKey.CreateEncryptor(), CryptoStreamMode.Write);
//crStream.FlushFinalBlock();


}
catch (NAEException ex)
{
Logger.LogError("Error in Decryption --> " + ex.Message);
}
finally
{
inputChar = null;
decryptedChar = null;
fSource.Flush();
fDestination.Flush();
fDestination.Close();
fSource.Close();
}

Thanks,
Narasimha