wireless keyboard volume issue

The wireless keyboard on my daughters imac (10.6.8 snowleopard) was working fine. She uses a laptop so I am repurposing this for my own use. I did a full factory reinstall using the discs and everything is fine, but now the keyboard won't change volume using f10/f11. It does what the other functions for those keys (weather, calculator etc.). I checked and the use fn button under keyboard is NOT checked.

Can someone tell me why resetting to factory settings may have done this and what to do about it.

Thanks.

 

Thanks. Turns out it was an updating issue. After I went from 10.5 to 10.6 bingo the keyboard worked fine.