In the Ubuntu operating system, the keys that Gladivs SSC use to take screenshots are assigned by default to a series of tools that are part of the core of Gnome. When we press the combination of keys, those tools interfere with Gladivs Simple Screen Capture. To avoid this, we must simply modify the keyboard preferences. To do this go to: System Settings > Keyboard > Shortcuts:
In the menu on the left, select the block ' Screenshots ' and customize the two shortcuts that are selected (the assignments by default for [Print Screen] and [CTRL] + [Print Screen]). If you want you can assign another combination of keys that not interfere with Gladivs SSC; alternatively, you can disable the function if you press the [BACKSPACE] key.
As you maked these changes, Gladivs SSC will take the screnshots like you see in the monitor.