JavaFx fxml Button doesn't appear in GridPane - javafx

Question

I'm trying this for a long time. This is my Fxml Code. When I run a JavaFx Application with this Fxml, the button is nowhere. What am I doing wrong?
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.chart.CategoryAxis?>
<?import javafx.scene.chart.LineChart?>
<?import javafx.scene.chart.NumberAxis?>
<?import javafx.scene.control.TableColumn?>
<?import javafx.scene.control.TableView?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.VBox?>
<?import javafx.scene.text.Font?>
<?import javafx.scene.text.Text?>
<VBox prefHeight="1080.0" prefWidth="1920.0" xmlns="http://javafx.com/javafx/9.0.1" xmlns:fx="http://javafx.com/fxml/1">
<children>
<GridPane maxHeight="-1.0" maxWidth="-1.0" mouseTransparent="true" prefHeight="800.0" prefWidth="800.0" VBox.vgrow="ALWAYS">
<children>
<HBox spacing="10" alignment="bottom_right" GridPane.columnIndex="0" GridPane.rowIndex="0"
>
<Button text="Sign In"
onAction="#handleCreateNewCarButtonAction"/>
</HBox>
<Text fontSmoothingType="LCD" layoutX="17.0" layoutY="53.0" strokeType="OUTSIDE" strokeWidth="0.0" text="Name = Auto Bezeichnung, FL = Corner Weight FL, FR = Corner Weight FR, RL = Corner Weight RL, RR = Corner Weight RR, sAC_C = Corner Weight FL, sAC_B = Slip Angle Coefficient B, sAC_E = Slip Angle Coefficient E, LC_KA = Load Coefficient KA, LC_KB = Load Coefficient KB, Delete = Auto entfernen, Show = Auto im Chart anzeigen" wrappingWidth="622.7230573003446">
<font>
<Font name="Arial Nova Light" size="12.0" />
</font></Text>
<LineChart alternativeColumnFillVisible="true" layoutX="648.0" layoutY="98.0" prefHeight="455.0" prefWidth="578.0" title="Car Chart" GridPane.columnIndex="2" GridPane.rowIndex="1">
<xAxis>
<CategoryAxis side="BOTTOM" />
</xAxis>
<yAxis>
<NumberAxis side="LEFT" />
</yAxis>
</LineChart>
<TableView layoutX="20.0" layoutY="126.0" prefHeight="403.0" prefWidth="615.0" GridPane.columnIndex="1" GridPane.rowIndex="1">
<columns>
</columns>
</TableView>
</children>
</GridPane>
</children>
</VBox>
<TableView >
<columns>
<TableColumn prefWidth="50.0" text="Name" />
<TableColumn prefWidth="50.0" text="FL" />
<TableColumn prefWidth="50.0" text="FR" />
<TableColumn prefWidth="50.0" text="RL" />
<TableColumn prefWidth="50.0" text="RR" />
<TableColumn prefWidth="50.0" text="sAC_C" />
<TableColumn prefWidth="50.0" text="sAC_B" />
<TableColumn prefWidth="50.0" text="sAC_E" />
<TableColumn prefWidth="50.0" text="LC_KA" />
<TableColumn prefWidth="50.0" text="LC_KB" />
<TableColumn prefWidth="50.0" text="Delete" />
<TableColumn prefWidth="50.0" text="Show" />
</columns>
</TableView>