Yeah, I looked that up and all it said about the trainer not registering the F key press was that on your keyboard you should have some kind of a "F-key lock" as in kinda the same as caps, etc.
Dunno what it means tho. I've honestly never heard of such a feature in a keyboard let alone seen one.
EDIT: I looked further into this on my end. When PayDay 2 is running in the background and I should be able to enable the trainer ingame, instead it says "Game not found!" on the bottom left of the program window.
Don't know whats up with that since I do have the game running and still, it wont recognize it.
[Edited by nto2602, 8/23/2013 5:37:12 PM]
did you give the trainer admin priviledges? that is right there in the FAQ