title: permuted Monitor results after a screenshot
body: <p>My Code should grab me a screenshot from one of my Monitors. The expected result is to get an Image of the second screen but what i get is a screenshot from the first Monitor. 
  (the same happens if i try to get a screenshot of the first Monitor then i just get a one from the second screen)
  I've already checked the screen Settings (Windows 7) and verified and identified which screen is the first and which one is the second. Can anyone explain this to me ? thanks in Advance. </p>
  
  <pre><code>from mss import mss
  import cv2
  with mss() as sct:
      filename = sct.shot(mon=2, output='screenshot.png') 
      img_bgr = cv2.imread('screenshot.png')
      cv2.imshow('image', img_bgr)
  </code></pre>
  
  <p>expected output: Screenshot of monitor 2</p>
  
  <p>actual Output: Screenshot of monitor 1</p>