When using the JFBContent plugin, in the parameters section, make sure it's set to show for Front Page articles as well. It's possible the page you're trying to show is actually a FrontPage layout, which looks like a blog, but is a little different internally to Joomla. Also, let us know if you're using K2 to display your articles, or something other than core Joomla Content.
Finally, feel free to send us a URL to your page, as that may help us narrow down possible causes.
Thanks!