When I connect a cable from my Toshiba laptop (running Windows 7) to my Vizio TV I can see on the TV what I see on the laptop but I can hear only from the laptop's internal speaker. I've tried this using 2 different HDMI cables and with 2 different Vizio TVs. I've verified in my laptop that the Realtec sound driver is enabled (but that's only possible when the laptop is connected to the TV) and selected as default. What can I do to hear the laptop video through the TV?