connection reset exception while using ftp clinet of apache commons-net-1.3

Hi Experts

I am using commons-net-1.3 of apache, to retrive files from ftp.

this is my function

            ftp = new FTPClient();

            int reply;
            ftp.connect(ftpServer);
            System.out.println("Connected to " + ftpServer + ".");

            // After connection attempt, you should check the reply code to
            // verify success.
            reply = ftp.getReplyCode();

            if (!FTPReply.isPositiveCompletion(reply)) {
                  ftp.disconnect();
                  throw new Exception("FTP server refused connection.");
            }
            ftp.login(ftpUsername, ftpPassword);
            ftp.setFileType(FTPClient.BINARY_FILE_TYPE);

            // Use passive mode as default because most of us are
            // behind firewalls these days.
            ftp.enterLocalPassiveMode();

            ByteArrayOutputStream baos = new ByteArrayOutputStream();

            ftp.retrieveFile(remote, baos);
            
            byte[] ret = baos.toByteArray();

            try {
                  tmpp = ftp.logout();
            } catch (Exception e) {
                       // here I get the exception
                  system.out.println("DEBUG - ftp logout problem\r\n"+StringUtils
                              .getStackTrace(e));
            }

            
            if (ftp.isConnected()) {            
                  try {
                        ftp.disconnect();
                  } catch (IOException f) {

                  }
            }


and I am get exception almost every time when invoking ftp.logout 

this is the exception

java.net.SocketException: Connection reset
        at java.net.SocketInputStream.read(SocketInputStream.java:168)
        at java.io.BufferedInputStream.read1(BufferedInputStream.java:256)
        at java.io.BufferedInputStream.read(BufferedInputStream.java:317)
        at java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
        at java.io.BufferedInputStream.read(BufferedInputStream.java:237)
        at org.apache.commons.net.telnet.TelnetInputStream.__read(TelnetInputStream.java:114)
        at org.apache.commons.net.telnet.TelnetInputStream.run(TelnetInputStream.java:535)
        at java.lang.Thread.run(Thread.java:619)



do you know what is the problem and how can i solve it ?

thanks