The Epson 711 cartridges use ink level chips that get "tripped" once the ink level drops to a refillable level. Once this happens, the printer won't work with the cartridge even if you refill it. You will need to reset the chip along with refilling the ink to get the cartridge to work again. What's more, the chips on a 711 cartridge are different from those on older models, so some resetters won't work on them.
Purchase a ninepin cartridge chip resetter for Epson cartridges, which can be found at many online retailers and some computer speciality shops.
Press the resetter against the Epson cartridge so all nine pins line up with the nine copper contacts on the chip. In order to do this correctly and see the light on the resetter, hold the cartridge upside down.
Look for the light on the resetter to come on and turn green. If it turns red, the contacts and pins are not properly aligned. Separate the two and try again.
Wait for the green light to flash and then shut off--this usually takes about three seconds. This is the signal that the chip has been reset.
Refill the cartridge with the correct shade of ink. This involves drilling a hole in the cartridge top (where the target is) with a thumb drill and injecting the ink into the cartridge with a syringe bottle.