I recently downloaded the ScreenCloud app from the Ubuntu Software Center, and coming from Windows 7, it acts a lot like the "Lightshot" program.
Like the Lightshot program on Windows, I would like to be able to hit the PrtScn button on my keyboard in order to take a "Select Area" screenshot with ScreenCloud.
So, in order to do that, I went to ScreenCloud>Preferences>HotKeys>double clicked on "Capture Selection" and hit the PrtScn button, and it didn't work.
I made sure the Gnome-Screenshot was un-installed by going to the Terminal and typing:
sudo apt-get remove gnome-screenshot
so that shouldn't be interfering with it. I also tried other combinations and was fine. (Except the default "Shift>Alt>2". I was un-able to get it to go back to that.)