Blank window using Javafx - javafx

Question

I made a window by using the screen builder program, but after I run it, only a white blank window appears. I think the problem that all variables , which are lblOUTPUT, aren't assigned. I'm a beginner at Scene builder and have been really struggling with this issue because it's my first work.
FXmain
package javaapplication6;
import java.io.IOException;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
/**
*
* #author ammar
*/
public class FXMain extends Application {
#Override
public void start(Stage stage) throws IOException {
Parent root = FXMLLoader.load(getClass().getResource("/javaapplication6/FXML.fxml"));
Scene scene = new Scene(root, 600, 400);
stage.setScene(scene);
stage.setTitle("Kilometer to miles converter");
stage.show();
}
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
launch(args);
}
}
FXMLcontroller:
enter code here
package javaapplication6;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
/**
* FXML Controller class
*
* #author ammar
*/
public class FXMLController implements Initializable {
#FXML
private Label lblOUTPUT;
#FXML
private Button btnCONVERT;
#FXML
private TextField txtKm;
/**
* Initializes the controller class.
*/
#Override
public void initialize(URL url, ResourceBundle rb) {
// TODO
}
}

Answer 1

Ok, I solved after two hours of struggling, I just click the run button in the NetBeans (looks like a play button) and after that, right-click on the main class, then run the file, and it worked!.