JavaFX label.getText() returns nothing in another class

Question

I need that label values (num, cost) to be displayed in Bank.java from Work-window.java
num = random int value
cost = int value

Code Work-window.java

package s.lab9;
import java.io.IOException;
import java.util.Random;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.stage.Stage;
public class WorkWindow {
    @FXML
    private Button enter;
    @FXML
    private Button payment;
    public int a;
    @FXML
    private TextField ticket;
    private ActionEvent event;
    private Stage stage;
    private Scene scene;
    private Parent root;
    @FXML
    public Label num;
    @FXML
    public Label cost;
    public WorkWindow(){ }
    public void click(ActionEvent event) throws IOException {
        String b= (ticket.getText());
        Random rnd= new Random();

        if (b.equals(String.valueOf(1))){
            a= rnd.nextInt(1000);
            num.setText(String.valueOf(a));
            cost.setText(String.valueOf(500));
        }
        if (b.equals(String.valueOf(2))){
            a= rnd.nextInt(1000);
            num.setText(String.valueOf(a));
            cost.setText(String.valueOf(10000));
        }
        if (b.equals(String.valueOf(3))){
            a= rnd.nextInt(1000);
            num.setText(String.valueOf(a));
            cost.setText(String.valueOf(10));
        }
    }


    public void switchtoPay(ActionEvent event) throws IOException{
        FXMLLoader loader = new FXMLLoader(getClass().getResource("Bank.fxml"));
        root = loader.load();
        Bank bank = loader.getController();
        bank.display2(num.getText(), cost.getText());

        payment.getScene().getWindow().hide();
        root = FXMLLoader.load(getClass().getResource("Payment.fxml"));
        Stage stage = new Stage();
        stage.setTitle("Payment");
        stage.setScene(new Scene(root));
        stage.show();
    }
}

Code Bank.java

package s.lab9;
import javafx.fxml.FXML;
import javafx.scene.control.Label;
public class Bank {
    @FXML
    private Label cart;
    @FXML
    public Label ticket;
    @FXML
    public Label cost1;
    public void display(String numcart){
    cart.setText(numcart);   }
    public void display2(String num, String cost){
    ticket.setText(num);
    cost1.setText(cost);
    }  }

Btw method display1 works correct, but display 2 isn't, Idk where i did mistake. fx:id:controllers assigned correctly, there are have prefWidth, so they cannot be "empty"