I am trying to set up Sling TV on a new Vizio M322i-B1. We have Comcast with a Cisco RNG200N cable box. The cable box is connected to Comcast through a coaxial cable. I set up an HDMI cable to the TV directly, and the TV works fine. But when I connect an HDMI cable from the RNG200N to the HDMI In port on the Slingbox, then connect an HDMI cable from the HDMI Out port to the TV, it does not pass the video through to the TV. I get stuck on the Test Your Remote step of the Setup. Sometimes the video flashes on for an instant, but most of the time the video is just blank, while the audio is working. The IR does not help, and I am sure that I really am using an RNG200N cable box. Please help!