To make it work, set the following xmodmappings:
\
keycode 174 = XF86AudioLowerVolume
keycode 176 = XF86AudioRaiseVolume
keycode 160 = XF86AudioMute
keycode 162 = XF86AudioPlay
keycode 164 = XF86AudioStop
keycode 144 = XF86AudioPrev
keycode 153 = XF86AudioNext
keycode 236 = XF86Mail
keycode 130 = XF86HomePage
keycode 223 = XF86Sleep
keycode 161 = XF86Calculator
keycode 230 = XF86Favorites
E.g. add this to a file in your homedir and load it with xmodmap from your .xsession file.