Apps :: No plugins in Firefox?

Have the latest Firefox and dsl 1.2.1. I tried to install RealPlayer, no problem. But now if I try to configure so, that a link on a web page would open the RP it doesn't work. If I check the plugins from the Firefox preferences, the "page" is totally empty! Any ideas, what is happening? I also set the PATH so that the RP is defined there, but no help