I cannot get my Nikon D600 or D300 to tether with LR 5.4 running on my Windows 8.1 laptop. Both cameras tether fine with LR 5.4 running on my Windows 7 desktop. Unfortunately, I need tethering to work on my laptop, not my desktop. Any idea why these cameras won't tether on a Win 8.1 system? I've tried all the troubleshooting tips.