Windows Application Error: Length of the data to decrypt is invalid

Hi Developers,

I have created a new windows form application for Decrypt a string with password. Its working fine. 

But sometime if the length is too it throws the following error.

"Length of the data to decrypt is invalid"

 AES password : 8468A97B4373415365537265744B6579746869834973215365637261745B6579

        public static byte[] AES_DECRYPT(string text, string hexPassword)
        {
            byte[] originalBytes = HexStringToByte(text);
            byte[] passwordBytes = HexStringToByte(hexPassword);
            byte[] encryptedBytes = null;

            using (MemoryStream ms = new MemoryStream())
            {
                using (RijndaelManaged AES = new RijndaelManaged())
                {
                    AES.Padding = PaddingMode.Zeros;
                    AES.Key = passwordBytes;
                    AES.Mode = CipherMode.ECB;
                    
                    using (CryptoStream cs = new CryptoStream(ms, AES.CreateDecryptor(), CryptoStreamMode.Write))
                    {
                        cs.Write(originalBytes, 0, originalBytes.Length);
                        cs.Close();
                    }
                    encryptedBytes = ms.ToArray();
                }

            }
            return encryptedBytes;
        }

        private static byte[] HexStringToByte(string hexString)
        {
            try
            {
                int bytesCount = (hexString.Length) / 2;
                byte[] bytes = new byte[bytesCount];
                for (int x = 0; x < bytesCount; ++x)
                {
                    bytes[x] = Convert.ToByte(hexString.Substring(x * 2, 2), 16);
                }
                return bytes;
            }
            catch
            {
                throw;
            }
        }

        private static byte[] HexStringToByte(string hexString)
        {
            try
            {
                int bytesCount = (hexString.Length) / 2;
                byte[] bytes = new byte[bytesCount];
                for (int x = 0; x < bytesCount; ++x)
                {
                    bytes[x] = Convert.ToByte(hexString.Substring(x * 2, 2), 16);
                }
                return bytes;
            }
            catch
            {
                throw;
            }
        }

plese suggest me how to fix this error. Am using the following code 

Thanks & Regards

Paul.S