normally only flightws booked with va as they need to be a certain fare code to get an upgrade with miles.
The flights with vh are discounted so you cant upgrade them with miles.
the miles upgradeable flights are normally a bit more expensive as they are more flexible so not the cheap ones you can get either which is a bit of a pain.
When I worked for va we had loads of people call up looking to upgrade the vh flights but they have their own fare code and are not upgradeable