Canon i560 printer's black cartridge not working?

Hi I%26#039;ve been using only the black and the cyan cartridge and recently after changing the black cartridge the cyan one got finished. Now If I try to print anything in gray scale NOTHING prints but the white A4 papers come out slowly as if the print nozzle is at work, but nothing is printed. Does this mean I%26#039;ve got a problem with my black ink or do I need to get another cyan cartridge to get the whole thing to work again ?|||Try getting the other ink cartridges to go along with the black one. Some printers don%26#039;t print unless all of the cartridges are installed properly. Sorry if this doesn%26#039;t help, but I can%26#039;t think of anything else.