I notice that when I'm playing GW2 I can press the volume keys on my keyboard and the volume OSD goes up and down but the volume doesn't change. If I click the volume icon in the systray I can adjust the volume. I have searched for ages but I seem to be the only person having this issue.

I changed the sound settings to disallow apps from getting exclusive control of volume.

How can I get the multimedia keys to control volume in games?