Methode .add in codenameone pour un attribut de type datePicker

package com.mycompany.gui;

import com.codename1.ui.Button;
import com.codename1.ui.ComboBox;
import com.codename1.ui.Form;
import com.codename1.ui.TextField;
//import com.company.Entite.Etat;
import com.company.Entite.Event;
//import com.company.Entite.Type;
import com.mycompany.Service.ServiceEvent;
import java.util.Date;
import javafx.scene.control.DatePicker;

public class HomeForm {
    Form f;
    DatePicker ddatedebut;
    TextField tlieu;
    TextField tlibelle;
    TextField tnombreticket;
    DatePicker ddatefin;
    TextField tprixunitaire;
    ComboBox ctype;
    Button btnajout, btnaff;

    public HomeForm() {
        f = new Form("home");
        ddatedebut = new DatePicker();
        tlieu = new TextField("", "lieu");
        tlibelle = new TextField("", "libelle");
        tnombreticket = new TextField("", "nombreticket");
        ddatedebut = new DatePicker();
        tprixunitaire = new TextField("", "prixunitaire");
        ctype = new ComboBox("", "type");
        btnajout = new Button("ajouter");
        btnaff = new Button("Affichage");
        f.add(ddatedebut); // erreur
        f.add(tlieu);
        f.add(tlibelle);
        f.add(tnombreticket);
        f.add(ddatefin); // erreur
        f.add(tprixunitaire);
        f.add(ctype);
        f.add(btnajout);
        f.add(btnaff);
        btnajout.addActionListener((e) -> {
            ServiceEvent ser = new ServiceEvent();
            Event ev = new Event(0, ddatedebut.getDate(), tlieu.getText(), tlibelle.getText(), Integer.parseInt(tnombreticket.getText()), ddatefin.getText(), Integer.parseInt(tnb_exemplaire.getText()));
            ser.ajouter(ev);
            f.show();
        });
        btnaff.addActionListener((e) -> {
            Affichage a = new Affichage();
            a.getF().show();
        });
    }

    public Form getF() {
        return f;
    }

    public void setF(Form f) {
        this.f = f;
    }

    public TextField getTnom() {
        return tlibelle;
    }

    public void setTnom(TextField tnom) {
        this.tlibelle = tnom;
    }
}