New Wireless Keyboard Problem

Hi Guys:

I did a quick search and couldn't find a solution for this. I have an IMac (last generation with OSX 10.5.8) I just purchased a new wireless apple keyboard - the F keys don't work as they should. I want to turn up and down volume, etc as marked. The USB keyboard works correctly.
Thanks in advance

Fixed it -- for anyone else that had this problem, all I had to do was check for updates and there was one there for the "aluminum keyboard" I didn't check that first and should have but I had just updated the computer recently - I guess the operating system doesn't look for that update until you add the keyboard.