The key is bound on [P], and even though i change it, it doesn't enter the photo mode.

Are you running it through galaxy?
If so try starting it from the .exe
Do you have other background apps running that might be interfering with it?

I used the stand alone installers and left the default P key and it works for me.
Well, except that it can't actually take a screenshot.

I do run it via Galaxy, and I intent to play it via Galaxy.

I meant to try running it without galaxy, just to see if galaxy is the problem.