Unable to take screenshot on Samsung Galaxy S7
If taking a screenshot with hardware keys don't so seem to work for you, you can use gestures to take a screenshot instead:  

Activate gestures: go to Settings &gt; Motions.
Inside the Motion menu, look for Hand Motions.
Check the Palm Swipe to capture.


Once you have activated the gesture, you can now grab a screenshot:

Go to the screen that you want to take a screenshot of.

Now swipe the edge of your hand from right to left and vice versa, horizontally.


This edge-to-edge swipe gesture may take you a few tries to master, but it makes taking screenshots so much easier and quicker.