my F7 till F12 function for media and volume on my keyboard Imac don't work

Bought a new keyboard. The function F7 till F12 is not working, the media and volume functions. Nothing is happening while i press these functions

Actually i bought the new keyboard because of this problem on my old keyboard!

Already tried System Preferences > Keyboard > Keyboard tab > Check "use all F1, F2 , etc, keys as standard function keys. NOT working while the text "use all....." is not showing up in om my PC

Thanks