If you are using a WholesaleWidgets.com guaranteed compatible, the fix is easy!
Just hit print until it goes away.
Why?
Risograph owns a patent on the computer chip. A compatible computer chip is nearly the same (but not exactly as to avoid any patent infringements), and as a result, the minor difference causes the machine to tell you that it doesn't recognize the chip. So, by hitting print a few more times, it forces the machine to recognize the chip, and it will perform beautifully!
This is the Riso RZ User's Guide