logitech K400 plus keyboard [print screen] function inoperable

anyone shed a light on why my new k400+ keyboard cant take screenshot? i mulled around logitech options program, found nothing. pressed FN and back key, nada..tried combo other keys, still nothing. i like this keyboard and hate to return it.

My K400r has a Prt Scn key around the top right of the keyboard, I then paste the image within Painshop pro.
Not at my PC so can't provide screenshot.
Edit: It appears in your case it's the function + back keys but as they're not working try just the back key as under the settings the function keys may be reversed - on my keyboard there's a box to tick to reverse the F+keys.
By default, the top row of keys on your K400 Plus keyboard are assigned to navigation and media controls. You can set the keyboard to only use standard F1 - F12 functions using Logitech Options software.

NOTE: If you don’t have Logitech Options, you can download it from the Wireless Touch Keyboard K400 Plus Downloads page.

To set the function keys to use only standard functions:
Start Logitech Options:
Start > All Programs > Logitech > Logitech Options
Select the Keyboard tab in the upper left corner of the window.
In the bottom left hand corner of the window, check Use F1-F12 as standard function keys. Your selection is automatically saved.

its still a mystery why i cant use print screen even after go through all other steps. so for now, ill have to use my pc's main keyboard to take screenshot. why i have second keyboard, dont ask lol. see, in snipping shot these keys dont work to take screenshot

Instead of using Print Screen, use Snipping Tool

no worries. ill just use my pc's print screen option. i dont think i set up the keyboard the first time properly...usually i dont follow instructions thoroughly lol,

cheers

edit - i found the solution. [FN] key + [windows ] key + [back] keys allow me to take screenshot.