ZXing Barcode Scanner does not activate Flash LED

I have the following Code to Scan Barcodes with ZXing:

           mscanner.UseCustomOverlay = false;

            MobileBarcodeScanningOptions scanoptions = new MobileBarcodeScanningOptions();

            scanoptions.TryInverted = true;
            //mscanner.ToggleTorch();

            mscanner.TopText = "Barcode Scanner";
            mscanner.Torch(true);
            mscanner.FlashButtonText = "Blitz";


            var result = await mscanner.Scan(scanoptions);

            DisplayResult(result);

I tried to activate the LED Flash of the Android Device with ToggleTorch() and with Torch(true). But the Flash Light does not turn on.

How can i activate the Flashlight in ZXing?

The required permissions are Camera and Flashlight.