530 error during FTP Upload

[C# Programming]

Hi I am I want Ftp Upload File but I have The remote server returned error: (530) did not at logon.
what is problem ?

FtpWebRequest Istek;
try
{
Istek = (FtpWebRequest)FtpWebRequest.Create(new Uri(@"Ftp://" + HostName));
Istek.UseBinary = true;
Istek.Credentials = new NetworkCredential(HostName, Password);
Istek.Method = WebRequestMethods.Ftp.ListDirectory;

WebResponse elcavab = Istek.GetResponse();