JPanel组件不在我想要的地方

Question

public class PLogin extends JPanel {

private JButton loginButton;
private JLabel usernameLabel;
private JTextField loginField;
private JLabel passwordLabel;
private JPasswordField passwordField;
private JScrollPane scroller;
private JTextArea status;

public PLogin()
{
    loginButton = new JButton("Login");
    add(usernameLabel = new JLabel("Username"));
    add(loginField = new JTextField(20));
    add(passwordLabel = new JLabel("Password "));
    add(passwordField = new JPasswordField(20));
    add(loginButton, BorderLayout.CENTER);
    status = new JTextArea(null, "Waiting", 5, 15);
    status.setEditable(false);
    scroller = new JScrollPane(status);
    scroller.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
    add(scroller, BorderLayout.PAGE_END);
}

这是我的登录GUI窗格的代码。

由于某种原因，滚动条和登录按钮彼此相邻。

Username : UsernameField
Password: PasswordField
Login    Scroller

我宁愿拥有

Login
Scroller

我已尝试使用BorderLayout.CENTER和BorderLayout.SOUTH - 任何想法？