Arch Linux

I have just installed arch linux in my Samsung laptop (np900x3j).

I can not enable the backlight of my keyboard. I have tried the instructions of this link:

https://wiki.archlinux.org/index.php/Keyboard_backlight

but I am getting the following error with the kb-light.py script:

<code>
Traceback (most recent call last):
File "/usr/local/bin/kb-light.py", line 26, in <module>
print(kb_light_set(int(sys.argv[2])))
File "/usr/local/bin/kb-light.py", line 11, in kb_light_set
current = kbd_backlight.GetBrightness()
File "/usr/lib/python3.7/site-packages/dbus/proxies.py", line 70, in __call__
return self._proxy_method(*args, **keywords)
File "/usr/lib/python3.7/site-packages/dbus/proxies.py", line 145, in __call__
**keywords)
File "/usr/lib/python3.7/site-packages/dbus/connection.py", line 651, in call_blocking
message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.UnknownMethod: No such interface “org.freedesktop.UPower.KbdBacklight” on object at path /org/freedesktop/UPower/KbdBacklight
</code>

I have also found this bug whitch is closed as solved:

https://bbs.archlinux.org/viewtopic.php?id=240392

However I have followed all the instruction in all comments and they did not work for me.