title: The 'Avg. Time on Page' is zero on Google Analytics
body: <p>I am using Google Analytics to trace and analyze my website, but i found more than 90% of 'Avg. Time on Page' is zero(see the screen shot below). I searched a lot and found most of the answers are the user closed that page directly and didn't go to next page so the 'Avg. Time on Page' is zero, but i am sure this is not my case. 
  Could any body know the reason or any clue? Thanks a lot in advance!</p>
  
  <p><img src="https://i.stack.imgur.com/BTupI.png" alt="enter image description here"></p>