LOL

OK - that was helpful. You're editing the link to the chat room - which is good. But since it's showing as 'sigma_chat' in the online table - we need to alter the query to grab users at that location - right now it's looking for people on pages you don't have.
I think this query is used twice.... but basically find this:
<br /> SELECT COUNT(*)<br /> FROM {$config['tbprefix']}Online<br /> WHERE O_What = 'chatheader'<br /> OR O_What = 'chatroom'<br /> OR O_What = 'chat'<br />
And change it to this:
<br /> SELECT COUNT(*)<br /> FROM {$config['tbprefix']}Online<br /> WHERE O_What = 'sigma_chat'<br />