I have a 6400 series Samsung Smart TV connected to a settop cable box via HDMI and also connected to a Yamaha RX-A820 A/V Receiver. All connections are HDMI. In the TV menu>sound>digital audio out the Dolby Digital and DTS options are not available only PCM and DTS Neo:2.5 are available. I have the newest HDMI cables which I thought is supposed to carry the Dolby Digital signal as well has High Def video. Why are the Dolby Digital and DTS options greyed out and not available?