请教 gridbaglayout布局

明明是从gridx=0, gridy=0开始布局的，不过发现部件离panel顶部距离很远，没用填充。试了archor想放在顶部也没用，这是怎么回事？panel是加在一个frame里，不受其他部分影响。部分代码：protected static JPanel PanelDemo () {
            JPanel panel = new JPanel(false);
            JLabel team = new JLabel("<html><font size=4 color =red>XX</font></html>",SwingConstants.CENTER);
            JLabel description = new JLabel("");
            
            JButton sbutton1 = new JButton("add");
            JButton sbutton2 = new JButton("remove");
            JList listPanelleft = new JList();
listPanelleft.setFixedCellWidth(150);
listPanelleft.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
JScrollPane teamlist = new JScrollPane(listPanelleft);
            
            Border border = LineBorder.createGrayLineBorder();
            panel.setBorder(border);
            team.setBorder(border);
            description.setBorder(border);
            
            panel.setLayout(new GridBagLayout());
            GridBagConstraints c = new GridBagConstraints();
            
            c.weightx = 0.5;
            c.fill = GridBagConstraints.BOTH;
           
            c.anchor=GridBagConstraints.PAGE_START;
            c.gridwidth = 1;
            c.gridx = 0;
            c.gridy = 0; 
            panel.add(team,c);
            
            c.gridheight = 3;
            c.gridx = 0;
            c.gridy = 1; 
            panel.add(teamlist,c);
            
            c.gridheight = 1;
            c.gridwidth = 3;
            c.gridx = 0;
            c.gridy=4;
panel.add(description,c);

c.gridwidth = 1;
c.gridx = 1;
            c.gridy=2;
            panel.add(sbutton1,c);
            
            c.gridheight = 1;
            c.gridx = 1;
            c.gridy=3;
            panel.add(sbutton2,c);
       
            
            return panel;
        }