If your Brother ink cartridges are not recognize by your printer, there might be a bad contact between the cartridge chip and your printer, the cartridge chip is on the end of the cartridge.

To troubleshoot this issue, please remove the cartridge from the printer.  Gently clean the gold contact chip with a Q-tip or an eraser.  Disconnect the power cord from the wall outlet and wait for 10-15 seconds, plug the power cord back to the wall outlet and then reinsert the cartridge.