Unless you can provide some more technical information, this falls into the category of a customer support issue that should be handled by the plugin provider if possible.
Some useful information to know would be: Which plugin are you using? Which Wordpress theme? What kind of troubleshooting have you already done? Be specific.
If you cannot provide details of a more technical and detailed nature, please look for answers with the plugin provider's support team.
(After looking at the pages you provided, I can only assume you mean
the Sharaholic plugin is the plugin which is not displaying on a
particular post.)
Sharaholic has a thorough support page here: Shareaholic Helpdesk
A post about Related Content not showing: Related Content is not
showing up on my Wordpress blog
An extensive troubleshooting walkthrough: The Ultimate
Troubleshooting Guide
And a page for submitting new support requests: Submit new
request