SwingBean - ComboModelClass não carrega itens

public class UsuariosComboModel extends DefaultComboBoxModel{

	/**
	 * 
	 */
	private static final long serialVersionUID = -5180102350569140475L;

	public UsuariosComboModel(){
		UsuariosDAO usuariosDAO = new UsuariosDAO();
		List values = usuariosDAO.selectAll();
		Iterator it = values.iterator();
		while(it.hasNext()){
			addElement(it.next());
		}
	}
}

public class UsuariosComboModel extends DefaultComboBoxModel{

	/**
	 * 
	 */
	private static final long serialVersionUID = -5180102350569140475L;

	public UsuariosComboModel(){
		addElement("Usuario1");
                addElement("Usuario2");
	}
}