installed Plugins aren't listed

Hello,

first of all sorry for my bad english...

I have just installed Openfire 3.9.3 on my server (debian 7).

When I add a plugin from the "available Plugins"-list, it takes some seconds to install untill it turns green,

and afterwards if i look under "Plugins" there it says that i haven't installed any plugins.

In the "Available Plugins"-list i am also not able to add this plugin any more,

instead of the plus there is no icon now.

I have already tried to reinstall openfire, also tried to manually add the plugins with the "Upload Plugin"-form in "Plugins",

also tried to add it directly to /var/lib/openfire/plugins ... always the same result...

Is someone else also having this problem or does anyone know an answer to this?

Thanks,

Raphael