Magic Keyboard Issue: Volume and Brightness Keys Not Working on 2019 iMac

i recently purchased a new magic keyboard for my 2019 iMac. i told the rep at apple what machine i had and i was advised to purchase this keyboard. first issue if this is not the correct keyboard: I live in another country so .. going to the apple store in NYC is not possible.

here i am with a keyboard which doesn't work. I've searched for solution .. and found some info. tried it. doesn't work.

i have NO FN key.

toggling the F1 keys on and off doesn't work.

using FN10 and 11 doesn't work

[Edited by Moderator]