Combo Box JavaFx with FXML

<ComboBox>
    <items>
        <FXCollections fx:factory="observableArrayList">
            <String fx:value="NVT" />
            <String fx:value="Bezig" />
            <String fx:value="Positief" />
            <String fx:value="Negatief" />
        </FXCollections>
    </items>
    <value>
        <String fx:value="NVT" />
    </value>
</ComboBox>