I just recently used ReMask 5 to remove a subject from a background. Since the subject was pulling on a compound bow I wanted to make sure I got the bow strings and cutouts along the bow into the cutout mask.
I tried using the Color Range Brush by selecting the Color Range, then the red removal tool and then sampling the background I wanted to remove with the eye-dropper. Everything I tried failed.
For the Color Range brush it only affects either the Keep/Cut color you have selected and the Color Range slide affects the shades of the color selected.
Try using the Transparency Brushes as you can define 2 colors … green for keep and red for remove at the same time. It allows you to select a foreground color and a color to be removed from ‘behind’ that color, for example a wedding veil, a chain link fence etc.