Preset Key variable

[Avator]

I want to set a variable for a keyboard key. So I made a global variable Preset - Key. However, I can't seem to use this variable in my 'Player X pressed Key down' event. There's a list of key variables and the list is empty.

Is this because it's an event? And if that's the reason, then why is there the possibility to choose variables in the event? And why make it possible to create Key variables, but can't place it anywhere (because I checked and there are no actions who use a Key variable)?
Or is there another reason why the variable doesn't show up in that list? I've tried restarting GE.