jradiobutton w jtable

witam
mam umieszczone w tabeli różne typy pól jradiobutton i jcheckbox. Problem pojawia się w momencie zaznaczania jradiobutton można zaznaczyć kilka zamiast tylko jednego(są dodane do ButtonGroup), w chwili gdy rozciągnę ramkę lub kliknę na inne pole(różne niż radiobutton ), zostaje zaznaczony radiobutton, który zaznaczono jako ostatni.Brakuje jakby odświezania? [???] Oto kod:

package testy;

import java.awt.Component;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import javax.swing.ButtonGroup;
import javax.swing.DefaultCellEditor;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JRadioButton;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.event.TableModelEvent;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.TableCellRenderer;

class RadioButtonRenderer implements TableCellRenderer {

    public Component getTableCellRendererComponent(JTable table, Object value,
            boolean isSelected, boolean hasFocus, int row, int column) {
        if (value == null) {
            return null;
        }
        return (Component) value;
    }
}

class RadioButtonEditor extends DefaultCellEditor implements
ItemListener {

    private JRadioButton button;

    public RadioButtonEditor(JCheckBox checkBox) {
        super(checkBox);
    }

    public Component getTableCellEditorComponent(JTable table, Object value,
            boolean isSelected, int row, int column) {
        if (value == null) {
            return null;
        }
        button = (JRadioButton) value;
        button.addItemListener(this);

        return (Component) value;
    }

    public Object getCellEditorValue() {
        button.removeItemListener(this);
        return button;
    }

    public void itemStateChanged(ItemEvent e) {
        super.fireEditingStopped();
    }
}

public class JRBTable extends JFrame {

    public JRBTable() {

        AbstractTableModel dm = new AbstractTableModel() {

            String title[] = {"OSOBA", "RESP", "CHECK"};
            public Object[][] cells = {
                {1, new JRadioButton(), false},
                {2, new JRadioButton(), false},
                {3, new JRadioButton(), false}};

            public Class<?> getColumnClass(int c) {
                return cells[0][c].getClass();
            }

            public String getColumnName(int c) {
                return title[c];
            }

            public int getRowCount() {

                return cells.length;
            }

            public int getColumnCount() {

                return cells[0].length;
            }

            public Object getValueAt(int r, int c) {
                return cells[r][c];
            }

            @Override
            public void setValueAt(Object obj, int r, int c) {
                cells[r][c] = obj;

            }

            @Override
            public boolean isCellEditable(int r, int c) {

                return c == RESP || c == CHECK;
            }
            public int RESP = 1, CHECK = 2;
        };
        JTable table = new JTable(dm) {

            public void tableChanged(TableModelEvent e) {
                super.tableChanged(e);
                repaint();

            }
        };

        ButtonGroup group1 = new ButtonGroup();
        group1.add((JRadioButton) dm.getValueAt(0, 1));
        group1.add((JRadioButton) dm.getValueAt(1, 1));
        group1.add((JRadioButton) dm.getValueAt(2, 1));

        table.getColumn("RESP").setCellRenderer(new RadioButtonRenderer());
        table.getColumn("RESP").setCellEditor(
                new RadioButtonEditor(new JCheckBox()));


        JScrollPane scroll = new JScrollPane(table);
        getContentPane().add(scroll);
        setSize(200, 140);
        setVisible(true);
    }

    public static void main(String[] args) {
        JRBTable frame = new JRBTable();
        frame.setDefaultCloseOperation(EXIT_ON_CLOSE);

    }
}

Jakieś pomysły?