acpi_video doesn't works?

According to 'man acpi_video', acpi_video.ko provides those variables:

hw.acpi.video.<device>.active
hw.acpi.video.<device>.levels
hw.acpi.video.<device>.brightness
hw.acpi.video.<device>.fullpower
hw.acpi.video.<device>.economy

This is on my laptop:

[(14:58)(91.42%):/home/toxa ] kldunload acpi_video.ko
[(14:58)(91.42%):/home/toxa ] sysctl -a|grep video
hw.acpi.reset_video: 0
[(14:58)(91.42%):/home/toxa ] kldload acpi_video.ko
[(14:59)(91.42%):/home/toxa ] sysctl -a|grep video
hw.acpi.reset_video: 0

There is absolutely no any kernel messages on console when
loading/unloading acoi_video.ko.
Does my vaio laptop lacks any acpi video features?

Thanks for advance