Issue with Add-on pack

I installed the Add-on Pack for NIS 2009 on my kids' computer a few weeks ago and set the security level.  Today when I tested it, the setting in NIS showed that it was not installed.  When I tried to reinstall it, I got the error that a version was already installed...  So after uninstalling the Add-on pack and reinstalling the most current version, it still does not show up in the NIS settings.  In other words, the Add-on pack is installed but inaccessible and unusable.

 

Any ideas?

 

Thanks.