I wonder if you accidentally disabled it? Choose Video|Filters|Perspective and see if the Enabled checkbox is checked.


> I was trying to correct for the perspective in the
> attached picture below. I applied the filter then
> when I begin adding  axis, calibration stick and point
> mass the video returns to its unfiltered state before
> I can track the marble's movement. Not sure what I
> am doing wrong or misunderstanding. I did read the
> help file on perspective filter.