What I did to make it work (Win7-x64): 
	
	
	
		
		
		
			
		
		
	
	
Launch 
STEAM , go to "
Library", select "
Sniper 4", right-click on "
Sniper 4" to select "
Properties", select tab "
Local Files" and click on "
Browse Local Files.."
It will open a window to:
(W7-x64) C:\Program Files (x86)\Steam\steamapps\common\Sniper Elite 4\
(W7-x32) C:\Program Files\Steam\steamapps\common\Sniper Elite 4\
Go into folder "
Launcher", right-click "
SniperElite4.exe" to select "
Properties" and select "
Compatibility" tab to set a check-mark on "
Run this program as an administrator". Click on "
Apply" and then "
OK".
The trainer "
Sniper Elite 4  V1.5.2 DX11 Trainer +6 MrAntiFun.EXE" (on the desktop) is also set to "
Run this program as an administrator"
Launching:
- With the "Sniper 4" icon (on the desktop), launch it and then click on  "PLAY"
 
- Go through the opening, select the "saved game" or "game" you want and start the actual game
 
- Wait until it is finished loading and that you can control your character around, press ESC (menu) then ALT-TAB back to desktop
 
- Launch the "Trainer" and click on the running tab to return back to the Sniper 4 game (which will still be at ESC menu)
 
- Press the desired keys F1-F4 and you will hear "Cheat Activated" or "Cheat De-Activated" depending of the key press
 
- Options::
- F1 = God Mode
 
- F2 = Inf.Breath
 
- F3 = No Reload
 
- F4 = Inf.Ammo + Inf.Gadget
 
- F5 = UnDetected *not working for me*
 
 
- Then press ESC to return to in your game and play!
 
* Since 
F5 is currently reserved for the "quick save" for the game - I guess this is why it's not working!
I even tried editing the hotkey in game to another F# - 
and nothing, "unDetected" not working
I also even tried editing the hotkey in trainer to another F# - 
same... nothing
Everything else works! So if you saved your game and closed out, then want to play later, rinse and repeat the "
Launching" sequence.
It does work (except F5) as I'm still currently playing it as I wrote this!
*edit - still working for me!
Please keep in mind that anti-virus software will consider the trainer to be a virus. It's a false positive, meaning since it does inject code into a program (like the game as example) then it will be considered a virus.
THIS TRAINER IS NOT INFECTED OR A VIRUS!!! as long you got it from here!
- Make certain to apply the appropriate rule/exception to your anti-virus software. To find out how to add it on your system, Google "
How do you add an exception to INSERT_YOUR_ANTI-VIRUS_SOFTWARE_NAME_HERE" and follow the steps to allow the trainer to run without fear of deletion by your anti-virus software.
   I do hope this helps out some more!   
Before I forget... Thank You 
MrAntiFun for your great work!!