I have tried connecting my cable box (Motorola DCT3416(Comcast) via hdmi cabling to my 2006 Sony Bravia LCD 40" tv, which has 3 hdmi input plugs. The tv does not get a picture or sound. I also tried connecting a Sony blu-ray BDPS390 to the tv via hdmi cabling. It did not work. This was tried with cabling direcly to the tvt. Is there some setting or something I have not done or done wrong?