data coding AES

[Lolalola]

Hi,
why i can coding only 128 bytes text?

Work:
string plainText = "1234567890123456";
Don't work:
string plainText = "12345678901234561";
Don't work:
string plainText = "123456789012345";

string plainText = "1234567890123456";
            byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);

            byte[] keyBytes = System.Text.Encoding.UTF8.GetBytes("1234567890123456");

            byte[] initVectorBytes = System.Text.Encoding.UTF8.GetBytes("1234567890123456");

            RijndaelManaged symmetricKey = new RijndaelManaged();
            symmetricKey.Mode = CipherMode.CBC;
            symmetricKey.Padding = PaddingMode.Zeros;

            ICryptoTransform encryptor = symmetricKey.CreateDecryptor(keyBytes, initVectorBytes);

            MemoryStream memoryStream = new MemoryStream();

            CryptoStream cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write);

            cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);

            cryptoStream.FlushFinalBlock();

            byte[] cipherTextBytes = memoryStream.ToArray();

            memoryStream.Close();
            cryptoStream.Close();

            string cipherText = Convert.ToBase64String(cipherTextBytes);

            Console.ReadLine();

[kvprajapati]

>why i can coding only 128 bytes text?

You must use a supported key length (128, 192, 256) appropriate for your algorithm of choice.

Wiki reference: http://en.wikipedia.org/wiki/Advanced_Encryption_Standard