The HP 61 Tri-color cartridge was a replacement for a similar one that stopped working even though it was still half full. After working for several weeks I suddenly started getting a message that the color cartridge "was not compatible with the printer" being used. even though it was still half full.. I removed the cartridge and put it back in the printer several times but kept getting the same message. It would not let me go any further with that days printing. I lost two days use of my printer. The cartridge was purchased at a leading office supply store and was packaged with a HP 61 Black as a "combo" pac.