I just bought an hdmi cord and a lightening hdmi adapter & I plugged up my iphone to the adapter and to the hdmi cord & then the hdmi cord to the back of my tv. It shows up on the screen but then when I go to play a movie or music the sound only comes out of my phone and not the tv. I have an older model yamaha av sound receiver and that doesn't have a setting for hdmi or an hdmi port. How can I get the sound to play through the tv?