Comment 29 for bug 251665

the use of fn-keys on vaio models depends on the module "sony-laptop" previously named "sonypi".
so first, verify that the module is correctly loaded.
"lsmod | grep -i sony"
then, the link beetween the fn-keys module and traditionnal keycodes are made through HAL (Hardware Abstraction Layer ). If something goes wrong there, xev and the traditionnal programs for keybiddings debug won't work.
I think your bug lies there.