I don’t know why, but it will not work with Vegas 9. I was using it with 8.0. I discovered this a few weeks ago when I upgraded to 9. The other problem I ran into was crashes when rendering. It didn’t happen all of the time, but often enough that I gave up and bought the Ciniforms Neo Scene product for $129 which trans-codes into an intermediate format before you import the video into Vegas. If you find something better please post back.
Goodluck!
Mike