DES解密时提示“要解密的数据的长度无效。”,该如何解决

DES解密时提示“要解密的数据的长度无效。”
用DES加解密，调试的过程中，在解密方法里面出现异常

  ///
/// DEC 加密过程
///
public string Encrypt(string pToEncrypt, string sKey)
{
DESCryptoServiceProvider des = new DESCryptoServiceProvider();　//把字符串放到byte数组中

byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);
//byte[]　inputByteArray=Encoding.Unicode.GetBytes(pToEncrypt);

des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);　//建立加密对象的密钥和偏移量
des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);　 //原文使用ASCIIEncoding.ASCII方法的GetBytes方法
MemoryStream ms = new MemoryStream();　　 //使得输入密码必须输入英文文本
CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);

cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();

StringBuilder ret = new StringBuilder();
foreach (byte b in ms.ToArray())
{
ret.AppendFormat("{0:X2}", b);
}
ret.ToString();
return ret.ToString();
}








  ///
  /// DEC 解密过程
  ///
  public string Decrypt(string pToDecrypt, string sKey)
  {
  DESCryptoServiceProvider des = new DESCryptoServiceProvider();

  byte[] inputByteArray = new byte[pToDecrypt.Length / 2];
  for (int x = 0; x < pToDecrypt.Length / 2; x++)
  {
  int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));
  inputByteArray[x] = (byte)i;
  }

  des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);　//建立加密对象的密钥和偏移量，此值重要，不能修改
  des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
  MemoryStream ms = new MemoryStream();
  CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);

  cs.Write(inputByteArray, 0, inputByteArray.Length);
  cs.FlushFinalBlock();//异常：要解密的数据的长度无效

  StringBuilder ret = new StringBuilder();　//建立StringBuild对象，CreateDecrypt使用的是流对象，必须把解密后的文本变成流对象

  return System.Text.Encoding.Default.GetString(ms.ToArray());
  }

请教各位，多谢！！！

------解决方案--------------------------------------------------------
是不是由于数据库里的字段长度太小,导致字符被截取？？
------解决方案--------------------------------------------------------
我用的一直没有问题啊 参考
/// <summary>
/// 进行DES加密。
/// </summary>
/// <param name="pToEncrypt">要加密的字符串。</param>
/// <param name="sKey">密钥，且必须为8位。</param>
/// <returns>以Base64格式返回的加密字符串。</returns>
public string Encrypt(string pToEncrypt, string sKey)
{
using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())
{
byte[] inputByteArray = Encoding.UTF8.GetBytes(pToEncrypt);
des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
System.IO.MemoryStream ms = new System.IO.MemoryStream();
using (CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();
cs.Close();
}
string str = Convert.ToBase64String(ms.ToArray());
ms.Close();
return str;
}
}

/**/