Print screen and copying

I have this very annoying problem, my print screen isn't working!
When i open a new document in photoshop after pressing print screen, and trying to paste it in, it won't show up!
I have also tried to paste it in via edit -> paste, but with no luck.
Also when i try to copy a image pressing the right mouse key and copy, then pasting it into a new document, buuut, it's not working.

this is very frustrating, and i would thank you so much if you knew what the problem is :)