I have a brand new 921 sitting in front of me, but unfortunately not in a working state. I have a single rg6 line running from my roof to the location of the 921 and was told by "advance technical support" at dish that the device would not function (won't even boot up) without two lines connected. Can anyone confirm/deny this? My 921 shows the Dish HDTV logo after being plugged in, but then the screen goes blank. After that, the orange online light blinks and the red light (top one) blinks less frequently. Thanks for any help.