Hi Rok
I am sorry I am not able to help because I have a similar problem. There is no secret to adding a plugin.
I uploaded new plugins to the plugin directory. The uploads were successful but they do not show in my blog.
I have been busy with it for two days. I deleted the blog and the mysql database and reinstalled. I have tried two different sites and two different PCs. I work on both PC’s simultaneously. The operating systems are both Windows XP
With service pack 3. I am using WordPress 2.04 ..it also did not work on the older version. It even removed some of the default plugins?
Best regards
Chris