Epson 840-Replaced Cartridges And Now It Won't Print Any Color

I have an Epson Workforce 840 printer. I replaced the black ink and the cyan with refillable cartridges and reset the cartridges. Everything printed fine. Then a month later, the magenta and yellow were running low so I replaced those cartridges and reset those with the rest of the replacement set I installed earlier that included the black and cyan. I checked the print levels and all of the cartridges are showing as full, both on the printer's display as well as from my computer (I am printing from my Mac Powerbook and my kids' Windows 7 laptops). I then did a nozzle check and a print head check, and now only the black prints out. I try and print a lined/ruled paper from the printer's onboard control panel that should print in cyan and it comes out blank.