[Plugin: upPrev Previous Post Animated Notification] Thumnail is not showing, only for one post it i

hello,

I have used this plugin. its working fine but its not showing the thumb nail.I have given the article title class to this plugn.

For only one post it is showing the thumbnail.

https://www.ads-software.com/extend/plugins/upprev-nytimes-style-next-post-jquery-animated-fly-in-button/