Add scroll into text area

How can I add the scroll bar to my text area. I have tried with this code but it's not working.

middlePanel=new JPanel();
middlePanel.setBorder(new TitledBorder(new EtchedBorder(), "Display Area"));

// create the middle panel components
display = new JTextArea(16, 58);
display.setEditable(false); // set textArea non-editable
scroll = new JScrollPane(display);
scroll.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);

//Add Textarea in to middle panel
middlePanel.add(scroll);
middlePanel.add(display);