Qt3D picking Point on plane

Pl45m4

I have a custom 3D scene with a planeEntity (QPlainMesh) as ground plate. To add more objects, I thought of selecting points (by RayCasting?!) and construct the new object there.

I've tried QScreenRayCaster and QRayCaster, but no one seems to work as expected.
I trigger my rayCast on Qt3DWindow::mousePressEvent.

How can I check if the ray has hit the plane or not? Currently I'm getting rayCast hits as soon as I click somewhere (doesnt matter where)

Do I really need to set a QLayer on every entity I want to hit with my ray?

I followed this (https://stackoverflow.com/questions/52666741/qscreenraycaster-not-finding-entity-what-am-i-doiong-wrong)

It's my first project in Qt3D, so dont blame me if I made beginner's mistakes :-)

Custom3DScene::Custom3DScene()
    : Qt3DExtras::Qt3DWindow()
{

    // Root entity
    m_rootEntity = new Qt3DCore::QEntity();

    m_rayCaster = new Qt3DRender::QRayCaster(m_rootEntity);
    m_rayCaster->setRunMode(Qt3DRender::QAbstractRayCaster::SingleShot);


    Qt3DRender::QLayer *pickableLayer = new Qt3DRender::QLayer(m_rootEntity);
    m_rayCaster->addLayer(pickableLayer);


    // Camera and Light
    // [ ... ]


    setRootEntity(m_rootEntity);


    // Plane data, transform and mesh
    // [ ... ]

    // Plane
    m_planeEntity = new Qt3DCore::QEntity(m_rootEntity);
    m_planeEntity->addComponent(planeMesh);
    m_planeEntity->addComponent(planeMaterial);
    m_planeEntity->addComponent(planeTransform);
    m_planeEntity->addComponent(pickableLayer);

    // Add rayCaster to rootEntity
    m_rootEntity->addComponent(m_rayCaster);

    connect(m_rayCaster, &Qt3DRender::QRayCaster::hitsChanged, this, &Custom3DScene::printCast); // just to see if ray was fired

}

TIA