[cellarius]

You need to log in every user at least once, so there is an entry in the session table that can be updated. If you don't do that, it will not work.

The cron runs every ten minutes, and you'll notice a difference only if
1) more time goes by than your normal session timeout (since after that time the user would normaly be no longer shown as currently online)
2) that user does not have any other activity during that time, since then he would be shown as currently online anyway.

I wonder how you would even tell if this addon works if you don't wait at least as long as your session timout. (But keep in mind there needs to be activity on your board for the cron to run, as explained above).

Once again: If you want further answers, mark this addon as installed. I have asked you to do that before, and I think its not too much to ask. I will ignore further questions until you do that.