Linux On My Samsung

I'm using NF310 with xfce4.
Session and system objects created fine.

# samsung-tools --backlight toggle

ERROR:dbus.proxies:Introspect error on :1.27:/Device/Backlight: dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.

# dbus --monitor
shows the last request is Introspect but no introspection reply.

How this can be?

Upd:
I can successfully communicate with system service:

[anni@anni ~]$ dbus-send --system --print-reply=literal --dest='org.voria.SamsungTools.System' '/Device/Wireless' org.voria.SamsungTools.System.Toggle
boolean true

But session service gives me:

[anni@anni ~]$ dbus-send --session --print-reply=literal --dest='org.voria.SamsungTools.Session' '/Device/Backlight' org.voria.SamsungTools.Session.Toggle
Error org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.