Visitor Logger Coding Help

[Ulujain]

I've downloaded and installed this "who is online" code. It worked fine for a few days, i.e it showed the last 8 people to my site, visitors and members, but after a couple of days, it would no longer update any visitor except logged-in members. so my site may say I have 14 guests, but this piece of code would only show me logged in.

I have it set up where visitors see "Guest" whereas I see IP address/name.

I've emptied the table, and reloaded it, but still no success.

Code is here:

http://www.ulujain.org/i-lastseen.php.txt

and the SQL file is here:

http://www.ulujain.org/lastseen1.sql

I'd love to know what is going on here.