It's because i had a white background... silly me. sorry for wasting time.
This wasn't a waste of time at all! I was stuck and couldn't figure out why CAF wouldn't work. You posting this helped me figure out exactly what my issue was.
I dont have a white background and still getting this. Should there be a layer under the layer with the mask?
I have this problem as well. Did you ever find a solution?
I have 1 layer, two masks set to subtract. Couldn't be simpler, I would have thought.
..but it just comes up with the message that All Target Frames Are Blank and it aborts the fill layer generation.