Joe -
That's not good to hear ... I'm a white t-shirt guy, so mine showed up great. My wife's shirt is grey, but the ladies shirt is a silver color, not charcoal. I have the same graphic, in blue, on the back of the white shirt.
Tim (Still_Fishin) ordered the same one ... I hope he doesn't have the same problem. If your new one (in blue) shows up and still isn't visible, let me know - I'll get on the horn and send Cafe Press the same graphic in white to be put on the darker shirts.
Their customer service is good, and the only "problem" we had with Cafe Press last year was duplicate orders. They didn't duplicate the charges, so a handful of people got free goodies - guess it was only a problem for Cafe Press & not us.
Please keep me informed so I can do what I need to on the graphic end. I will say that the inks, this year, appear to go more of into the fabric, rather than sit on top. The shirts last year felt almost screen printed, for being a direct-to-garment digital print, I was impressed. Maybe they changed their inks?