acpi_video doesn't work

Module is loaded (current within 2 days)

output:

# sysctl hw.acpi.video
hw.acpi.video.crt0.active: 1
hw.acpi.video.lcd0.active: 1
hw.acpi.video.tv0.active: 0

attempting to change:

# sysctl hw.acpi.video.lcd0.active=0
hw.acpi.video.lcd0.active: 1 -> 1

am I doing something wrong?

Scott