I was printing a color chart and step tablet and noticed that I couldn't see a difference between the last two dark steps of the tablet. When I looked closer under very bright illumination, the last step was actually slightly lighter then the next step. The RGB values were something like zero and maybe 8-12. Shining an LED flashlight through the paper, there's definitely less ink on the last step (that should be the darkest.) Paper is Red River UltraPro Gloss II with their profile (I think). Is this a profile issue or is there something else I should look at? It doesn't affect images because we're talking the blackest of the blacks, but it's also not the way things should be.

Thanks! I know it doesn't matter but it will probably bug me until I figure it out. One speculation is that the printer might avoid making a mess by limiting ink flow whenever it sees an RGB value of zero.