Logitech k400 keyboard - there is not a key to the left or right of shift

i got the logitech k400 keyboard to use with my macbook air and an external monitor. it's a little wireless keyboard with a built in trackpad.

when i got it, it worked great right away. i plugged in the the usb receiver and it worked just fine.

i took it to work where i also have a logitech keyboard but not one with a trackpad like the k400. the logitech unifying reciever says it will work with any logitech device that has that symbol on it. so it worked fine there too.

when i got back, the macbook air no longer recognizes the logitech keyboard. i've tried new batteries, all sorts of variations on restarting the laptop, taking batteries out and in, removing/replacing usb receiver.

when i try to go to system prefs for the macbook air and set up the keyboard, it wants me to press the key to the right of the shift key. well, on this keyboard, this not a key to the right of the shift key.

there is no software at the logitch site and their forums haven't yielded any results.

i don't understand why it worked and now it doesn't. i used it at home for two days before taking it to work so i know that it definitely was functioning as expected with the macbook air.

i'm not sure if it's a mac problem or logitech problem and i'm not sure how to figure that out.

any help would be appreciated.

thanks!