FTP下载/上传错误504

我正在尝试编写一个程序，它将从和FTP下载一些文件，压缩它们然后再次上传到相同的FTP位置。

我有它试图下载一个文件。如果失败，它将再次尝试。

如果没有错误，所有文件下载并上传文件。

如果下载时出现任何错误，它将在重新尝试时下载它们，但随后上传失败。

我想问题出在没有正确关闭连接上，但是我怎么也想不出来。

这是我的代码;我添加了失败的地方:

上传:

FileInfo fileInf = new FileInfo("directory" + zip + ".zip");
string uri = "ftp://address" + fileInf.Name;
FtpWebRequest reqFTP2;
reqFTP2 = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://address" + fileInf.Name));
reqFTP2.Credentials = new NetworkCredential("username", "password");
reqFTP2.KeepAlive = true;
reqFTP2.Method = WebRequestMethods.Ftp.UploadFile;
reqFTP2.UseBinary = true;
reqFTP2.ContentLength = fileInf.Length;
int buffLength = 2048;
byte[] buff = new byte[buffLength];
int contentLen;
FileStream fs = fileInf.OpenRead();
try
{
    Stream strm = reqFTP2.GetRequestStream(); //FAILS HERE
    contentLen = fs.Read(buff, 0, buffLength);
    while (contentLen != 0)
    {
        strm.Write(buff, 0, contentLen);
        contentLen = fs.Read(buff, 0, buffLength);
    }
    strm.Close();
    fs.Close();
}
catch (Exception ex)
{
}

下载:

int errorOccured = 0;
while (errorOccured < 1)
{
    FileStream outputStream = new FileStream("directory''" + file, FileMode.Create);
    FtpWebRequest reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://address/" + file));
    reqFTP.Credentials = new NetworkCredential("username", "password");
    try
    {
        reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;
        reqFTP.UseBinary = true;
        FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
        Stream ftpStream = response.GetResponseStream();
        long cl = response.ContentLength;
        int bufferSize = 2048;
        int readCount;
        byte[] buffer = new byte[bufferSize];
        readCount = ftpStream.Read(buffer, 0, bufferSize);
        while (readCount > 0)
        {
            outputStream.Write(buffer, 0, readCount);
            readCount = ftpStream.Read(buffer, 0, bufferSize);
        }
        ftpStream.Close();
        outputStream.Close();
        response.Close();
        errorOccured++;
    }
    catch (Exception er)
    {
        outputStream.Close();
    }