I have a Sony DVP-CX995V DVD player connected to a Hitachi 42HDS52A TV. I used a HDMI cable about 15ft long to connect the two. If I lay the cable on the floor it works fine. When I tried to run it under the floor the TV won't communicate with the DVD!!! I ran the cable along the floor joists and thought that there might be some interference with other power and signal wires near it. So I just looped the wire from one hole in the floor to the other. Still no communication. It always works above the floor. I have a heating duct it goes near and the cable for the TV, and some 120v romex for the outlets.