Cartridge not detected (by 6 users)

I like 7212Law have the same problem. I have put new cartridges in twice and have got "no cartridge" therefore your guru Soulvistor's answer is nonsense.

Change ink! It has a sensor that stops operation to ensure ink lines remain with ink in them
There should always be ink left in cartridge otherwise the printer would suck in air and air would turn in to bubbles in the ink line which become blank areas on your printing.

This problem seems to be caused by the gray horseshoe-shaped sensor behind the cartridges. I tried cleaning them with a cotton swab, and found that the "No Cartridge" message turned off when the swab was in the sensor.

So if you put something (like a tiny piece of cotton) in the cavity about halfway up the cartridge (so that it takes up space in the sensor when you replace the cartridge), you can trick the sensor into thinking the cartridge is there.
If it doesnt work the first time, try rearranging the cotton (or whatever you put) or putting more in.

If you are using or have used third party generic ink cartridges or refilled ink cartridges, the Cartridge Sensor printed circuit board may have been damaged. We have found that some third party generic ink cartridges leak onto the ink cartridge sensor circuit board causing an electrical short of the ink cartridge sensors. The damage from the leaked ink results in the machine displaying NO CARTRIDGE because the machine will no longer recognize the installed ink cartridge(s). Genuine Brother ink cartridges do not cause this issue because of the unique design developed to fit specifically in the Brother products. As long as a Brother cartridge has not been refilled, the Brother cartridge will not leak.