Ok...so the way my plugin works is to pull in what might be called the leading image..an example is here:
You'll see the RSS feed contains this leading image..its the very first thing in the description tag. If you look at your RSS feed, the description tag is closed off after the first sentence, so there is no image in your description tag.
<description><![CDATA[Hi Everyone! This post is about is about the popular trend of creating playlists for novels. Whether we prefer the solitude of a quiet library, music playing or the buzz of the city around us, everyone has a personal preference for how we like to read our books. How do you like to read your [...]]]></description>
As a result, the problem resides in your RSS feed having the description tag closed before any image is present. I would get the RSS feed fixed, and then you should be able to images show up in my plugin..and if you put the image first in the description tag, then you can control where it goes using the parameters in the plugin.
Let me know if you have any questions.