JFreeChart dosn't work

Hello everybody

I'm trying to make a line chart from JFreechart, but I just can't get it to work. The graph get its data from at 2-columun database (String, double). (The string is a date, represented as a String). The X-axis should be the different string, and the Y-axis should be the double values. I tried DefaultCategoryDataset, but every time I run it, an error occurs (i tried an example from here, with XY, and it didn't work either)

I could really use some help on this, as i'm completely lost. (It has been checked that the database contains the data)

public class Chart {

    Connection conn;
    Statement stmt;
    ResultSet rs;

    Chart(){
        try{
            Class.forName("org.sqlite.JDBC");
            conn = DriverManager.getConnection("jdbc:sqlite:projectdb.db");
            System.out.println("Database connection established");
            String dateinput;
            double temp;

            DefaultCategoryDataset dataset = new DefaultCategoryDataset();


            stmt = conn.createStatement();
            rs = stmt.executeQuery("SELECT * FROM data");
            while(rs.next()){
                dateinput = rs.getString(1);
                temp = rs.getDouble(2);
                dataset.addValue(temp, "", dateinput);
            }

            JFreeChart chart = ChartFactory.createLineChart(null,
                                                            "Time",
                                                            "Temperature",
                                                            dataset,
                                                            PlotOrientation.VERTICAL,
                                                            true,
                                                            true,
                                                            false);

            JFrame test = new JFrame();
            test.setVisible(true);

            ChartPanel chpanel = new ChartPanel(chart);
            chpanel.setPreferredSize(new Dimension(785, 440));
            chpanel.setMouseWheelEnabled(true);
            JPanel panel = new JPanel();
            panel.add(chpanel);
            test.add(panel);


        }
        catch(Exception e){
            System.out.println(e.getMessage());
        }        
    }
    public static void main(String[] args){
        new Chart();

        }
}