Sorry for any delay with a response to this thread.
Just to let everyone know, that after various tests, I found you can not use both F12 and PrintScreen is the same level test to take screen shots.
Example: Pressing F12 first, will not allow you to copy and paste a image into paint even if you made a screen capture with print screen and done correctly.
After taking a few shots to show the frame rate in the island levels i am currently testing, I found it was best to use print screen once first time, and then close out, make the picture in paint or something (as mentioned) and then repeat the process, reloading the level each time.
From memory if I used PrintScreen, then walked around the level and used F12 to take a second shot, it would delete the PrintScreen copy and when I would go to paste it in paint, No paste option was available.
Hope this helps anyone.