Do you have a static IP for the actual computer?
http://120.240.115.31/~jcraggs/ doesn't seem to work.
Also, check to see if there are any firewalls that are in operation that might block your ability to serve out html.
Finally, check your local computer to see if the Web server is running. The local default IP number for your computer should be "127.0.0.1" (no quotes). If you type that in and the Web site for your Mac comes up, you are serving out pages.
If not, you need to turn on Web services.
The troubleshoot with any net admin you might have to see what restrictions might be in place.