Synchronizing with Sockets

Question

I have a thread that performs a FTP Operation to upload all files from a directory to an FTP Server. Im using the enterprisedt FTP library.
I think there is something wrong with my synchronization process every time I try to transfer some files only a chuck of a single file is transferred and the program exits abnormally without continuing with the rest of the files.When I check the sever logs it complained of [an error closing connection: An established connection was aborted by the software in your host machine......An existing connection was forcibly closed by the remote host.]
Question:
1) Has anyone faced any similar problems with synchronzing with the FTP LIbray. If so how did you overcome the above problem.
2) If im wrong and there is a problem with the synchronization of the block object (new Object()) how do I fix the code so that I wait for the operation to finish before moving on to the next file.
3) Can anyone offer any tips of how the program can be efficient. Im using a scheduling scenario where this class is called from scheduler and the connection is initiated using a reference from the scheduler.
for(int i=0;i<files.length;i++)
synchronized(block){
     try{
          transferFile(transfer.getLocalDir(), transfer.getRemoteDir());
     catch(Exception e){
     onError(e.getMessage());
public void transferFile(String local, Sting remote) throws Exception{
try{
ftp.put(local,remote);
catch(FTPException e){
throw new Exception(e);
Thanks

Answer 1

Ive check the site again there is no mention of the ftp library being synchronous. However it is not thread safe and instructs the user to ensure the user does not try to access the same ftp object.
The website: http://www.enterprisedt.com/products/edtftpj/faq-answers.html#4
Besides without the synchronized method I would get the same result.