Qt3D signal not sent or not caught

Question

Based on the official example given in Qt, I try to catch keys inputs using Qt3DInput::QKeyboardHandler.

So after the following piece of code:

Qt3DCore::QTransform *sphereTransform = new Qt3DCore::QTransform;
OrbitTransformController *controller = new OrbitTransformController(sphereTransform);
controller->setTarget(sphereTransform);
controller->setRadius(20.0f);

I add :

Qt3DInput::QKeyboardHandler *keyboardHandler = new Qt3DInput::QKeyboardHandler(rootEntity);
keyboardHandler->setSourceDevice(new Qt3DInput::QKeyboardDevice(rootEntity));

QObject::connect(keyboardHandler,
                 &Qt3DInput::QKeyboardHandler::pressed,
                 controller,
                 &::OrbitTransformController::onPressed);

rootEntity->addComponent(keyboardHandler);

But the signal is never caught or maybe ever sent. What am I missing ? Attaching my object to another Qt3DCore::QEntity doesn't fix anything.

The official complete example without my adds : https://doc.qt.io/qt-6/qt3d-simple-cpp-example.html

EDIT 1:

I add more important code snippets with my comments:

orbittransformcontroller.h :

class OrbitTransformController : public QObject
{
    Q_OBJECT
    Q_PROPERTY(Qt3DCore::QTransform* target READ target WRITE setTarget NOTIFY targetChanged)
    Q_PROPERTY(float radius READ radius WRITE setRadius NOTIFY radiusChanged)
    Q_PROPERTY(float angle READ angle WRITE setAngle NOTIFY angleChanged)
public:
    OrbitTransformController(QObject *parent = 0);
    ...
public slots:
    // Begin my Code
    void onPressed(Qt3DInput::QKeyEvent *event);
    // End my Code
    ...
};

orbittransformcontroller.cpp :

...
// Begin my Code
void OrbitTransformController::onPressed(Qt3DInput::QKeyEvent *event)
{
    qDebug() << "OrbitTransformController::onPressed !";
}
// End my Code

the main.cpp :

Qt3DCore::QEntity *createScene()
{
    // The original code :
    ...
    Qt3DCore::QTransform *sphereTransform = new Qt3DCore::QTransform;
    OrbitTransformController *controller = new OrbitTransformController(sphereTransform);
    controller->setTarget(sphereTransform);
    controller->setRadius(20.0f);
    
    // Begin my Code
    Qt3DInput::QKeyboardHandler *keyboardHandler = new Qt3DInput::QKeyboardHandler(rootEntity);
    keyboardHandler->setSourceDevice(new Qt3DInput::QKeyboardDevice(rootEntity));

    QObject::connect(keyboardHandler, &Qt3DInput::QKeyboardHandler::pressed, controller, &::OrbitTransformController::onPressed);

    rootEntity->addComponent(keyboardHandler);
    // End my Code
    ...
}

Nothing more ! You will have noticed that Qt3D documentation and examples are quite light :(