I have a hp psc

I have a hp psc 2170 series all-in-one. At present I cannot get the printer to print or copy documents. I only have the one # 56 black print cartridge installed. It is a new cartridge and it has ink in it. The ink comes off the cartridge onto finger tip but it won't print everytime. Occassionally it will print a letter but usually not. I have checked the installation of cartridge and have reinstalled software but with no success.