Packer plugin problem ?

[[HUN]Peti]

When I open Configuration, and set fhRAR for rar files, it displays an error message that this isn't a wcx plugin or something, what I want to know is that how TC identifies wcx plugins:
a) So if I select it, it loads the plugin to check if it's working or not.
b) Scan the file for Version information or something like this.

If a, then the bug is in fhRAR, it doesn't load perfectly...
This may be because of different PCs, fhRAR is not compatibel with mine, but if so, why was it compatible with 2.6? I checked it with 2.6, and it's ok.
If b, then TC has changed the plugin identifying mechanism and that's why fhRAR doesn't "look like" a wcx plugin anymore.