My proposal should help eliminate the questions and is quite simple. Either split the messages into two, like:
- User Blah is doing something.
- User Blah is trying to do something but was denied due to lack of permissions.
I'm not sure how difficult this would be to do, but it would save a lot of user confusion (and numerous support queries). If it's possible but expensive, it could have a Load Setting (but my guess is that very few people click the Who Is Online link compared to other board activity).