Have you tried cleaning the head pins both of the cartridge and in the printer? If there's ink covering those pins, then it might caused the printer unable to transmit to the cartridge. Please take extra caution that these parts are highly sensitive. Using soft cloth or ear buds will do the trick.
p.s. Do check the 4 pins in the printer for the blue color, if all the pins still retractable (working springs) returning to its original position after pressing it down...then it should be ok...if not...then, you'll need to send it to canon for service.
Good Luck!
canonip, January 2010