I am sorry, there is no such animal as VGA HDMI! It is either: VGA; or HDMI! HDMI has an audio path, VGA does not! HDMI has ACK and REC protocols, VGA just has "give it to me!"
If you have VGA hooked up but don't have a separate audio cable of Red and WHITE, then that is why you are missing audio. The red and white provide audio!
It's kind of fun to do the impossible! -Walter Elias Disney