Calling Fxml file using Start Method which extends Application Class - javafx

Question

I want to make a new FXML file which has few Controls like Label. But when I run the application Some times the from is not Showing and Sometime when form is Showing label are not Showing.
I have written the following code:
DashBoard.fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.text.*?>
<?import java.lang.*?>
<?import java.net.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<AnchorPane id="AnchorPane" prefHeight="603.0" prefWidth="1063.0" styleClass="mainFxmlClass" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.DashBoard.DashBoardController">
<stylesheets>
<URL value="#dashboard.css" />
</stylesheets>
<children>
<Label fx:id="welcome" layoutX="403.0" layoutY="52.0" text="Label" />
</children>
</AnchorPane>
DashBoardController.java :
import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
/**
* FXML Controller class
*
* #author DELL
*/
public class DashBoardController implements Initializable {
/**
* Initializes the controller class.
*/
#FXML
private Label welcome;
#Override
public void initialize(URL url, ResourceBundle rb) {
// TODO
}
}
DashRun.java :
package com.DashBoard;
import javafx.application.Application;
import static javafx.application.Application.launch;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.image.Image;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
public class DashRun extends Application{
#Override
public void start(Stage stage) throws Exception {
Parent root = FXMLLoader.load(getClass().getResource("DashBoard.fxml"));
Scene scene = new Scene(root);
Label a = new Label();
stage.setTitle("Dash Board");
stage.setScene(scene);
stage.show();
}
public static void main(String[] args) {
launch(args);
}
}