PCSX2 HELP

I apologize if emulator talk is not something that's supposed to be discussed here, but I needed to ask this. So recently, I've been streaming PS2 games on my Twitch (Kingdom Hearts II: Final Mix precisely), and I was trying to test out the F8 button for screenshots (since I'll need it for the FF games for the FFWiki). However, it seems to do nothing. In fact, NONE of the F keys seem to do anything they're supposed to be doing. Would anyone happen to know why this would be at all?? I'm perplexed as to why it wouldn't work as advertised...

That wouldn't help when I need to take things in the heat of action though like abilities and the like. That's where I'd need the screenshot function the most. ^^;