Can't get the sound from my computer to come through on the TV?

I can never seem the sound to go out from my lenovo thinkpad yoga through the onelink dock out of my tv. I'm using a display to hdmi cord to connect the dock to my TV. It has worked once before. I went in to sound settings on the dock and selected hdmi device as the speakers but now that doesn't show up as a option. Also when the dock is plugged in the computer keeps making the sound that plays when something is ejected from the computer but it doesn't show anything as being ejected. I can't use the hdmi port on the computer because it doesn't carry audio so that's why i got the dock.