Your spot color for white might also need to be in all caps. In the default spot color table in Flexi, it's labeled "RDG_WHITE". Check on that, it might be a problem with naming. Also, if you use the clear calendared profiles, it should recognize the white swatch in Versaworks, then you will be able to play with how you want things ordered, white then cmyk or vice versa, or just white. Make sure you shake the white cartridge before using it and give yourself plenty of drying time.