The active users are being cached. Therefore you will have to refresh the board cache in order to see the updated counts. This was done in order to stress the server a little bit less.
The error you get in the ACP is because of me. I kind of made an error in the package and I'll update the package later today.
The reason you don't see the gallery statistics is probably because either the Add-On category or the scapegoat is not enabled. Click on the system-tab in your ACP and then on phpBB Statistics in the left sidebar.
Make sure the category Add-Ons is enabled. After that open the Add-Ons category and make sure that the one Add-On that is in there (probably scapegoat) is enabled.