I made it to the dark side of the rainbow, but I can't select 32 as a color value, only 0 and 64, so progression is locked.
Thanks for the tip. I actually wasn't getting credit last time because I had changed the starting color to gray, but after logging in today, it was reset to black, and I noticed I DID get credit. However, when I switched back to gray, and noticed I did NOT get credit until I changed back to black. So that seems like a glitch, maybe.
I've also noticed I have to end at 128, 64, 0 in order to achieve 64, 32, 0.