Toshiba Satellite Pro A300: Fn+F6 & Fn+F7 (screen brightness) not working

[m654321]

[size=1em]Have just set up LL3.0 on my sister's Toshiba Satellite Pro A300 - I've got a problem with the screen brightness control - the Fn key combinations for changing screen brightness (in a continuous fashion) are not working, i.e. Fn+F6, decrease; Fn+F7, increase brightness.[/size]

[size=1em]In an attempt to fix this I did the following, in the terminal, using gksudo leafpad /etc/default/grub: [/size]
[size=1em]changed GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"[/size]
[size=1em]to GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi="
[/size]
[size=1em]This didn't work so the next thing I tried was...
[/size]
[size=1em]changed GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" [/size]
[size=1em]to GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor[/size]"

[size=1em]This didn't work either.

I'd be grateful for any help on this, as full-screen brightness can be really tiring in the evening, as you know only too well, and the f.lux app (f.lux alters the quality & intensity of the PC screen's backlighting as a function of the time of day), which I use routinely on my setups, doesn't seem to function - I assume this is related to the screen brightness problem.[/size]

[size=1em]Thanks in advance for any help on this one...[/size][size=1em]
Mike[/size]