If you installed EM 7.1 just now, how did you install plug-ins for PS (CC?)? Please note that EM CC only manages extensions for CC applications such as PS CC. PS CS6 will not be listed in EM CC (You have to use EM CS6.). EM 7.1 lists installed plug-ins only if you have installed them with EM 7.0 before and didn't delete database file when you uninstalled EM 7.0. If you installed those plug-ins manually or database file has been deleted, EM CC will not list them.
I am using Photoshop 2014 CC and I have plugins for Topaz, Nik, and On One, plus DXO and others. None of them are usable in Photoshop (they are dimmed out). The Extension Manager doesn't see them either. What is the problem?