Alt-F4 not working?

[WhiteKnight]

I have a Logitech MX Duo and for some reason the Alt-F4 close window shortcut has stopped working. This is a really weird problem, any ideas?

 

[Elcs]

Check to see if F-Lock is on. It confused me when my Alt-F4 didnt work and that turned out to be the culprit.

 

[WhiteKnight]

Bingo, thanks!

 

[Elcs]

Its one of 2 things i dislike about my Duo.

The other one is no LED on the keyboard itself for Caps Lock.