why aren't my JLabels and JTextFields showing up in the JPanel?

I have a JDialog and inside it I have a JPanel that uses FlowLayout

now I've created 3 labels and text fields using the Netbeans GUI Builder, and I want to add 2 more text fields using code

I've adjusted the size of the panel so that when I add a new label and a textfield with a preferred size the new set of label - textfield will be under the previous set

somewhere in the JDialog I do something like this

        J开发者_StackOverflow中文版Label cores = new JLabel("Cores");
        cores.setPreferredSize(new Dimension(70,15));
        first = new JTextField();
        first.setPreferredSize(new Dimension(140,20));
        JLabel power = new JLabel("Power");
        power.setPreferredSize(new Dimension(70,15));
        second = new JTextField();
        second.setPreferredSize(new Dimension(140,20));
        panel2.add(cores);panel2.add(first);panel2.add(power);panel2.add(second);

when I compile the program, the labels don't show up and neither do the textfields

when I go down and click I have the following result

http://img684.imageshack.us/img684/13/unledlpy.png

if I type something, the text field appears

http://img5.imageshack.us/img5/6796/unledhig.png

the labels don't appear though, I don't think I made any changes to the properties, any help would be appreciated thanks

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Define the no of columns while creating object.
like this

JTextField jt=new JTextField(20);