ASP.NET

#region Password Util
   /// <summary>
   /// Encrypts a string using the SHA256 algorithm.
   /// </summary>
   public static string HashPassword(string plainMessage)
   {
       byte[] data = Encoding.UTF8.GetBytes(plainMessage);
       using (HashAlgorithm sha = new SHA256Managed())
       {
           byte[] encryptedBytes = sha.TransformFinalBlock(data, 0, data.Length);
           return Convert.ToBase64String(sha.Hash);
       }


   }


   #endregion

   protected void btnSubmit_Click(object sender, EventArgs e)
   {
       bo.UserID = txtUserId.Text;
       Password p = new Password(txtPassword.Text.ToString());
       String newpwd = p.SaltedPassword;
       System.Nullable<int> newsaltkey = p.Salt;
       bo.Encryptpwd = newpwd;
       bo.Saltkey = p.Salt;
       bo.Password = txtPassword.Text;

       passwordFormat = MembershipPasswordFormat.Hashed;
       if (passwordFormat == MembershipPasswordFormat.Hashed)
           bo.Blogpwd = HashPassword(txtPassword.Text);
       else
           bo.Blogpwd = txtPassword.Text;

<br />
protected void Button1_Click(object sender, EventArgs e)<br />
    {<br />
       <br />
        string connectionString = "provider=Microsoft.Jet.OLEDB.4.0;" + @"data source=D:\\image\db.mdb";<br />
        OleDbConnection connection2 = new OleDbConnection(connectionString);<br />
        string commandString = "Select Image from img where ImageCode = 1";<br />
        OleDbCommand command2 = new OleDbCommand(commandString, connection2);<br />
        connection2.Open();<br />
        byte[] m_objBitmap = (byte[])(command2.ExecuteScalar()); ;<br />
        connection2.Close();<br />
<br />
        Bitmap BitmapData = BmpDataFromBitmap(m_objBitmap);<br />
        MemoryStream ms = new MemoryStream();<br />
        Response.ContentType = "image/jpeg";<br />
        BitmapData.Save(ms,ImageFormat.Jpeg);<br />
        ms.Close();<br />
        <br />
    }<br />
    static public Bitmap BmpDataFromBitmap(byte[] BitmapData)<br />
    {<br />
        MemoryStream ms = new MemoryStream(BitmapData);<br />
        return (new Bitmap(ms));<br />
    }<br />
<br />

But i get error "Parameter is invalid" at line: