That is because you should just use the Direct Link
Here is how it looks when you select the direct link which is the second option
Now here look at the difference
THis is the link you used
http://imgur.com/a/ZeNra.png
This is mine
http://i.imgur.com/SKCCk6e.png
What you did wrong, is that you used Image Link and not Direct Link. Image Link is for URL stuff this is why the image doesn't show up.
Just use the Direct Link option and you fine.