Thank you for your post.
I don't have access to FileMaker Server 8.0v4, so I have to rely on the documentation.
The Read Me file that comes with FileMaker Server 8.0v4 is available in our Knowledge Base as article #6851.
I also noticed on the Apple web site the article "Mac OS X Server 10.4: Web service may not work after upgrade".
Let me know if any of these solutions don't help.