QNearFieldManager problem

[mrdebug]

In order to get an event when a mifare badge is readed by the nfc reader I have written these lines of code

    NearFieldManager= new QNearFieldManager(this);
    connect(NearFieldManager, SIGNAL(targetDetected(QNearFieldTarget*)), this, SLOT(targetDetected(QNearFieldTarget*)));
    NearFieldManager->startTargetDetection();

In the destructor I have these lines of code

        NearFieldManager->stopTargetDetection();
        delete NearFieldManager;

Now the problem is that, in an Android device, the nfc reader works only the first start of the app. After that no event will be emitted.
In order to get the nfc reader working again with my app I have to restart my mobile or unistall and reinstall it.
Are you working with this object and Android?