Swing elements not displaying properly

Hello! I am new to Java, having taken an online course in it. I am trying to write a very simple program. I'm starting with the UI. I have four elements: a label, a combo box, another label, and a button. When I run the program, I see the second label (element #3) followed by the combo box (element #2). The other elements do not display. I have not set a layout (I have tried a couple, but I am obviously doing it wrong as I get errors.) The relevant code is quoted here (do I need to include more?) and a picture of the app's display is attached. Are my mistakes obvious to anybody?

Thanks for any help you can give me, folks!

JLabel label1 = new JLabel();
label1.setText("Select number of players:");
panel1.add(label1);

String[] possiblePlayers = {"1", "2", "3", "4"};
JComboBox combo1 = new JComboBox(possiblePlayers);
combo1.setSelectedIndex(1); // Set default number of players to 2
panel1.add(combo1);

JLabel label2 = new JLabel();
label1.setText("Click to Continue:");
panel1.add(label2);

JButton button1 = new JButton();
button1.setText("Proceed");
panel1.add(button1);

OK, I found and fixed the error in the code for label2.