Excuse me, but there's one possibly obvious answer -
have you 'trained' your PC for your voice in the Windows voice recognition utility?
If you speak commands while voice attack is running, and look at the voice attack main display, it will say things like 'recognised' and then the command you said, or 'unrecognised' ...along with what it thought you said.
If it is recognising your commands, then your keybinds aren't set up (unlikely at this point), or more likely you don't have 'focus' on the elite window - on the Voice attack screen it ought to be reading 'send commands to active window'... as an example of #how to be ignored' I run another add on program for trading, and if I've clicked on one of that program's windows and don't click back on the elite window, then VA commands don't have any effect as they're trying to do things in my trading program rather my ship.
If it is NOT recognising your commands, no matter what you say it just says 'unrecognised': (and a bit of text showing what it thinks you said) then your computer isn't recognising what you say correctly, and you need to spend more time training it via your control panel 'Ease of access' voice recognition utility....depending on version of Windows.