The volume and brightness keys do not work on the new portable keyboard I got.

I've tired everything. The "use all F1,F2..." is unchecked, and I've switch some of the functions in "Exposé" but the volume buttons and brightness buttons still do nothing! I've looked all over the interent too and can't seem to find a solution...I've been working on this almost and hour now and I'm starting to get frustrated 😟 HELP