Hi
Further to my reply above....
" ....in order flip white text to black and the black background to white."
Why not use black text on a white background in the first place?
If you are doing the text through VP then you could add a blank white background clip (Under "Add Objects" tab.) and add black text to the overlay track. (In the text editor set the text to black and the text editor background to white so you can see it.)
Better still use black text and set the Full background option to white and then there would be no need for the Negative effect or a blank white background clip.
Nat