If your HP printer cannot recognize a new ink cartridge, How to Put Ink Into a HP Printer make sure to remove the protective tape and that the cartridge is compatible with your printer model. Take the cartridge out and put it in again, wipe the electrical contacts with a lint-free cloth and turn the printer back on. You can also update printer firmware in order to overcome the cartridge detection problem. If the problem persists, it could be a fault in the cartridge or the printer needs servicing. Check out other HP printer troubleshooting tips at Devicesfixes.