Notification erscheint nicht

@SuppressLint("NewApi") 
    private void setNotification(String weckpunktBezeichnung)
    {
        Intent intent = new Intent(getActivity().getApplicationContext(), DisableNotification.class);
        
        PendingIntent pendingIntent =
                PendingIntent.getActivity(getActivity().getApplicationContext(), 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
        
        NotificationManager notificationManager =  (NotificationManager) getActivity()
                                                .getSystemService(Context.NOTIFICATION_SERVICE);
        
        Notification.Builder notificationB = new Notification.Builder(getActivity().getApplicationContext())
                                                 .setSmallIcon(R.drawable.ic_launcher)
                                                 .setContentTitle("Weckpunkt aktiviert")
                                                 .setContentText(weckpunktBezeichnung)
                                                 .setAutoCancel(true)
                                                 .setDeleteIntent(pendingIntent);

        
        notificationManager.notify(DisableNotification.NOTIFICATION_ID, notificationB.build());
    }