Sometimes when you refill a HP or Lexmark cartridge you get dreaded message "Cartridge Not Recognized". What does this mean? It recognized cartridge before I refilled it! HP and Lexmark have print heads right on cartridge and if you'll notice there is some circuitry on side which also has electrical contacts that connect print head to printer. There are many contact points that must be made between cartridge and printer. If connection isn't perfect you will get error message.
There are a couple of things you can do to rectify this. First try snapping cartridge in and out a few times. If that doesn't work remove cartridge and clean off foil contacts with a Q-Tip dampened with alcohol.
Be careful not to wipe nozzles, where ink comes out, or you might contaminate ink inside cartridge.
Before you put cartridge back in use another Q-Tip dampened with alcohol and clean off contacts inside your printer where cartridge connects.