Function Button Doesn't Control Audio

[kkk5]

Hi!

I used to control the audio in my Kubuntu by holding the [Fn] button in my Acer laptop then press the UP arrow, but now I can't control it that way anymore. I have to click on the audio icon down right side of the screen, and control it manually. It's the [KDE Mixer - Playback Devices] that I have to access in order to change the volume. I want it like the old hardware way. How can I fix this?

[cariboo]

What did you do to your system before the buttons stopped working?