Swing : Progress monitor does not show up

Question

The progress monitor does not show up and also edt gets stacked whnen I call doInBackground(). Anybody that could help me out I would really appreciate it.

mainFrame is running on the edt but is created in another class.

    public void serializeAlbumsList(DefaultListModel<Album> albums) {
        SwingUtilities.invokeLater(new Runnable(){

            @Override
            public void run() {
                progressMonitor = new ProgressMonitor(mainFrame, "Please wait while saving your albums...", null, 0, 100);
            }

        });
        Serializer serializer = new Serializer(albums);
        try {
            serializer.doInBackground();
        } catch (Exception e) {
            e.printStackTrace();
        }       
    }

private class Serializer extends SwingWorker<Void, Void> implements PropertyChangeListener{
        int progress;
        private DefaultListModel<Album> albums;

        public Serializer(DefaultListModel<Album> albums) {
            this.albums = albums;
        }

        @Override
        protected Void doInBackground() throws Exception {
            setProgress(0);
            for (int i = 0; i < albums.size(); i++) {
                ObjectOutputStream os;
                try {
                    FileOutputStream fs = new FileOutputStream("Album" + i + ".ser");
                    os = new ObjectOutputStream(fs);
                    os.writeObject(albums.getElementAt(i));
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                    return null;
                }
                progress = i*(100/albums.size());
                setProgress(progress);
            }
            return null;
        }

        @Override
        public void propertyChange(PropertyChangeEvent e) {
            if (progressMonitor.isCanceled()) {
                cancel(true);
            } else if ("progress" == e.getPropertyName()) {
                int progress = ((Integer) e.getNewValue()).intValue();
                progressMonitor.setProgress(progress);
            }
        }
    }