Did you get an HDMI-VGA cable, or an HDMI-DVI adapter?
One is just a cable with 2 different connectors on it and wont do anything for your situation.
The other actually has a circuit board to convert the digital HDMI signal to VGA. You also have to make sure it is going the right way. The common model is VGA->HDMI meaning allowing an old laptop or device to display on a TV, you are doing the slightly less common HDMI->VGA