Joomla 1.6 is over 2 years old and is no longer supported by Joomla.org itself. Joomla 1.7 and Joomla 2.5 superceded that release. Joomla 2.5 is what is currently supported by Joomla.org itself. I'd highly, highly recommend moving to Joomla 2.5, which should be a very easy upgrade process (even though the version numbers make it seem like it may be more difficult). There are numerous security vulnerabilities and bugs in Joomla 1.6 that have been fixed in recent 2.5 release.
Finally, JFBConnect only officially supports Joomla 1.5, 2.5, and 3.0. Our releases may install on Joomla 1.6, but if you run into issues we may not be able to help without requiring you to upgrade the CMS. The proper version of JFBConnect to install for Joomla 1.6 would be the Joomla 2.5 release though, not the Joomla 1.5 version.
Hope that helps explain,