TR4520 Won't Print Black even though only the Color Cartridge Is Empty

[ckm]

I've been printing from a long succession of black cartridges while my color cartridge is empty.(no problems)

Now suddenly it won't print from black cartridge (I get popup saying color cartridge is empty). What can cause this ?

[Patrick]

Hi ckm,

The PIXMA TR4520 requires that both the black ink cartridge and color ink cartridge are both installed in the printer and that they both contain ink in order to use the printer.  To resolve this issue, please replace the color ink cartridge.