Java Programming

i have problem in transferring data through java socket
the funny thing is able to transfer from server to client but not from client to server with same code
here is the code that i transfer from client to server:

server download file code

public void downloadFile(){

         try{
            String fName =  serverIn.readUTF();
            String username = serverIn.readUTF();
            //int bytesRead;

            fName = getFileName(fName);
            System.out.println(fName);
            String fileFolder = System.getProperty("user.dir")+"\\ServerFTPFolder\\"+username+"\\"+fName;

            File f = new File(fileFolder);

            FileOutputStream fout=new FileOutputStream(f);
            BufferedOutputStream bos = new BufferedOutputStream(fout);
            int len;

            while ((len = serverIn.read(buffer)) > 0) {
                bos.write(buffer, 0, len);
                System.out.println("#" + len);
            }
            System.out.println("lennnnn"+len);
           
            System.out.println("file finish. sending object now...");
			this.sendObject(username);
			System.out.println("File Send Successfully");
             serverIn.close();
            bos.flush();
            bos.close();
            servSocket.close();
            clientSocket.close();
         }catch(Exception ex){
            System.out.println(ex);
            ex.printStackTrace();
         }

     }

upload code in client:

public void uploadFile(String fName){
         try{

                clientSocket = new Socket(ccon.ip, 6790);
                System.out.println("connecting to server");
                clientOut = new ObjectOutputStream(clientSocket.getOutputStream());
                clientIn =new ObjectInputStream (clientSocket.getInputStream());
                clientOut.flush();


            long start = System.currentTimeMillis();
            File f = new File(fName);
            
            clientOut.writeUTF(fName.toString());
            clientOut.writeUTF(ccon.userMatrix);
            clientOut.flush();

            statusLbl.setText("Status: Please wait! Transferring file...");
            statusLbl.setForeground(Color.RED);
            if(f.exists()){
                FileInputStream fin=new FileInputStream(f);
                BufferedInputStream bis = new BufferedInputStream(fin);
                int len = 0;
                while ((len = bis.read(buffer)) != -1) {
                    clientOut.write(buffer, 0, len);
                    clientOut.flush();
                    System.out.println("#" + len);
                }
                System.out.println("lennnn" + len);


             
                bis.close();
                long end = System.currentTimeMillis();
                System.out.println(end-start);

                FileTreeModel newObject = null;
                Object ftm = new Object();
                ftm = clientIn.readObject();
                System.out.println(ftm);
                newObject = (FileTreeModel) ftm;
                if(newObject!=null){
                    setTreeModel(newObject);
                }
            }
            else{
                System.out.println("file not exist!");
            }
            statusLbl.setText("Status: connected, ready for transferring");
            statusLbl.setForeground(Color.BLUE);
            clientSocket.close();
         }catch(Exception ex){
             ex.printStackTrace();
         }

     }

any help????