Why is my printer saying ink is uncapatible?

There is a circuit board that the ink cartridge fits onto, inside the print cartridge is a chip that registers with the printer to let it know that it is new. Sometimes ink gets onto the electrical contacts, this can be cleaned with cotton swab with alcohol. Make sure the contacts are clean and dry and also clean and dry the contacts on the ink cartridge.

Sometimes, there is a bug in the firmware that reads the cartridge and then tells it that it is empty, in this case try to update the firmware and you will probably have to replace the ink cartridge again.