Log in to site question?

I have been seeing this alot on my site. When some of my member's are in the chat box they are not loged into the site? I just don't understand that. Its been happening alot. Or i will be looking threw some of the thread and see the online button and they are not log in? Could someone please explain that if you can? It would be most helpful, just totally at a loss on this.

they are still logged in but just not showing because when the who's online refreshes, they have been logged into the chatroom, not the site.

also the whos logged in doesnt hold for very long i dont think and only done by refresh so if they havent refreshed and are posting in chat they wont appear on the online list.

okay thank you guys.