I'm having problems getting a Bartik subtheme going which uses colors.css - All I really need it do do is to reference a linked colors.css file. I've linked the external file in as you'd expect:

stylesheets[all][] = css/colors.css

However it seems that the theme is jumping between using this css file and a generated css file (I'm assuming this is part of the colors module). Disabling the colors module as well as changing the color back to the default doesn't seem to make any difference.

What is it that determines whether the generated colors.css or the defined colors.css is used?