Kega Fusiion/Gens - can't get emulator to recognise kb input.

Hey there this problem has been driving mental. I recently reinstalled an emulator on my machine to play some ol ROMs and stuff. Anyways when I went to configure the controller for the keyboard in Fusion (and gens) the define function simply did not respond to any inputs.

The emulator itself will respond to inputs (like esc for full screen or the various functions keyboard shortcuts) but input into the game does nothing, nor does the define function recognize the input. I was on windows 7 and even tried upgrading to win 7 to see if it fixes the problem. I think I managed to get the game to start once by spamming an implausibly large number of key combinations but the character just ended up running to the right without any control over him.

I've tried googling around but most of the answers involve "turn off/on scroll lock newb" or "something's capturing keyboard focus" - neither of which seems to have much impact since I've tried closing all apps and rebooting etc.

I'm using a razer black widow keyboard with now win 10.