When I try to post a comment (share link) on an article from my page which is actually a page I am using as an application in Facebook: https://apps.facebook.com/ids_newsletter/, Facebook chooses the feed thumbnail image of the post feed randomly from my page.

I tried using below to put a custom image for the post but nothing affected the post thumbnail. So what should I do?

<meta property="og:title" content="IDS June Newsletter" />
<meta property="og:description" content="Check this out" />
<meta property="og:image" content="MYSITEURL/Images/logobig.png" />
<meta property="og:image:type" content="image/png" />
<meta property="og:image:width" content="200" />
<meta property="og:image:height" content="200" />