Not clear, are you now in Sonar Platinum, or still in Sonar X3 ?
Have you tried holding your mouse on the bottom of the PRV window, and dragging it upwards to expose the controller view window at the bottom ? The default view is velocity, so you should see velocity lines down there.
That is, as described above by promidi, as long as you have "Show/Hide Controller Pane" turned on in the view menu.