TreeTablewView malfunction

Question

I am trying to display in treetableview all the members of a Citizen Class instance, but for some reason the it wont display a specific member while it displays other members! The member that isn't being displayed is: cWeapon under the column Weapon

there are 2 Classes:

1.Citizen

public class Citizen implements Comparable<Citizen> {
private String fullName, id;
private int birthYear, daysInQuarentine;
private boolean cWeapon;
private boolean inQuarantine;

public Citizen() {
    super();
}

public Citizen(String fullName, String id, int birthYear) {
    this.fullName = fullName;
    this.id = id;
    this.birthYear = birthYear;
    this.cWeapon = true;
}

public String getId() {
    return id;
}

public int getBirthYear() {
    return birthYear;
}

public String getFullName() {
    return fullName;
}

public int getDaysInQuarentine() {
    return daysInQuarentine;
}

public boolean iscWeapon() {
    return cWeapon;
}

public void setDaysInQuarentine(int daysInQuarentine) {
    this.daysInQuarentine = daysInQuarentine;
}

public boolean isInQuarantine() {
    return inQuarantine;
}

public void carryWeapon() {
    this.cWeapon = true;
}

@Override
public int compareTo(Citizen o) {
    return this.id.compareTo(o.getId());
}

@Override
public String toString() {
    return "ID: " + id + ", " + "FullName: " + fullName + ", " + "BirthYear: " + birthYear + ", " + ", "
            + "inQuarentine: " + inQuarantine;
}

2.Testing (JAVAFX)

public class Testing extends Application {

public static void main(String[] args) {
    launch(args);
}

@Override
public void start(Stage primaryStage) throws Exception {
    TreeTableView<Citizen> treeTableView = new TreeTableView<Citizen>();

    TreeTableColumn<Citizen, ?> col1 = new TreeTableColumn<>("Full Name");
    TreeTableColumn<Citizen, ?> col2 = new TreeTableColumn<>("ID");
    TreeTableColumn<Citizen, ?> col3 = new TreeTableColumn<>("Quarantine");
    TreeTableColumn<Citizen, ?> col4 = new TreeTableColumn<>("Carry Weapon");

    col1.setCellValueFactory(new TreeItemPropertyValueFactory<>("fullName"));
    col2.setCellValueFactory(new TreeItemPropertyValueFactory<>("id"));
    col3.setCellValueFactory(new TreeItemPropertyValueFactory<>("inQuarantine"));
    col4.setCellValueFactory(new TreeItemPropertyValueFactory<>("cWeapon"));

    treeTableView.getColumns().add(col1);
    treeTableView.getColumns().add(col2);
    treeTableView.getColumns().add(col3);
    treeTableView.getColumns().add(col4);

    TreeItem<Citizen> citizen = new TreeItem<Citizen>(new Citizen("Jason Bourne", "458878968", 1970));
    treeTableView.setRoot(citizen);

    VBox vBox = new VBox(5);
    vBox.getChildren().add(treeTableView);
    Scene scene = new Scene(vBox, 400, 200);
    primaryStage.setScene(scene);
    primaryStage.setTitle("Testing");
    primaryStage.show();
}

GUI Picture