First you have to compile frimware with this build option in `Makefile`.
NKRO_ENABLE = yes
2. After boot keyboard may be in **boot mode**(6KRO), you will need to replug keyboard to enable NKRO.
Try `Magic`**N** command(`LShift+RShift+N` by default) when **NKRO** still doesn't work. You can use this command to toggle between **NKRO** and **6KRO** mode temporarily. In some situations **NKRO** doesn't work you need to switch to **6KRO** mode.
3. Or use `Magic`**N** command to toggle NKRO function.(`LShift+RShift+N` by default)
If your firmeare built with `BOOTMAGIC_ENABLE` you need to turn its switch on by `BootMagic`**N** command(`Space+N` by default). This setting is stored in EEPROM and keeped over power cycles.