F1 and F2 keys won't change to standard function keys even after changing keyboard preferences.

I want to use the function keys on my MacBook Pro as standard function keys. I checked the box in keyboard settings that's supposed to change this, and I changed the Mission Control shortcuts that corresponded with function keys. F3-F12 all seem to have gotten the message, but F1 and F2 still change the screen brightness and won't work as standard function keys no matter what I do. How can I fix this?