Sounds like your hub might not have enough power for those two, do they do the startup LED dance when you start bfgminer?

Also little thought experiment for you...you started them up just now because LTC is on a tear again...why didn't you have them running this whole time and collecting a little LTC in the background for years during the bear market, and that LTC would have been worth hundreds now?

I always tell people, best time to mine is not now, but during bear markets when difficulty is lowest and you mine the most LTC with your devices.