xfce-power-manager does not dim

[psil0cybin]

xfce-power-manager does not dim on inactivity on lenovo g700 laptop.
all other graphical settings are fine, whta can I do to fix this

some information

lspci -k | grep -iA2 VGA
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
    Subsystem: Lenovo Device 3977
    Kernel driver in use: i915
 for interface in /sys/class/backlight/*; do echo -e "\n $interface"; cat $interface/{brightness,max_brightness,actual_brightness}; done

 /sys/class/backlight/acpi_video0
7
10
7

 /sys/class/backlight/intel_backlight
4882
4882
1301

and

Code:

BOOT_IMAGE=/boot/vmlinuz-3.2.0-59-generic root=UUID=5445fbf6-d7d5-4378-8ac7-69264731dcfb ro quiet splash acpi_osi=Linux vt.handoff=7