I've just started using TurboPrint so this is likely a dumb newbie question but here goes ... I'm printing from a registered version of TurboPrint (v.2.32-1) to an Epson 3880 under Linux Ubuntu 12.04. The Color/Grey Tone slider under the Color tab seems to have no effect on the color output. I've tried changing both the A (-20) and B sliders (-30) but the output looks the same in all cases. Any ideas about what I'm doing wrong? Thanks.
update: the Color Correction sliders do seem to work as expected, so now I'm even more stumped.