Java help

[Computer Acolyte]

Ok this is a very basic problem but I can't figure out what's wrong.
I'm learning the awt (Abstract Windowing Toolkit) package (I know it's old but that's what the Java book has)
Anyway, I wrote a small program just to see how it all fits together, it's supposed to give me a window titled "Animals" with 3 colored buttons.
Here's the code:

import java.awt.*;
public class TestAwt {
public static void main(String[] args) {
Frame frame=new Frame("Animals");
Panel panel=new Panel();
Button b1=new Button("Dog");
Button b2=new Button("Cat");
Button b3=new Button("Hamster");

b1.setForeground(Color.white);
b1.setBackground(Color.blue);
b2.setForeground(Color.white);
b2.setBackground(Color.blue);
b3.setForeground(Color.white);
b3.setBackground(Color.blue);

panel.setBackground(Color.blue);
panel.add(b1);
panel.add(b2);
panel.add(b3);

frame.add(panel);
frame.setVisible(true);
frame.setSize(200,200);

}
}

For some reason all it gives me is the frame (overall window) but no components inside (no buttons, no background [panel]), which is very strange, considering that this program (a simpler version of the previous one) works:

import java.awt.*;
public class Wtf {
public static void main(String[] args) {
Frame frame=new Frame("Alice in wonder land");
Panel panel=new Panel();
Button b=new Button("Press");
panel.add(b);
frame.add(panel);
frame.setSize(300,300);
frame.setVisible(true);
panel.setBackground(Color.black);

}
}

What am I missing here?