In case anyone reads this in the future, I had the url of the directory set to /ubbthreads/uploads/attachments, but the physical location of the files was in /var/ubbthreads/uploads. I had to create an Alias directive in the apache conf file to tell the server what the url should be. Then I had to create a directory config with the correct permissions so that the files could be displayed.
All of this was caused by my moving the directory from uploads/attachments under DocumentRoot to /var/ubbthreads/uploads for space reasons but not thinking through that the server needed to be told where that directory was now and had to have the correct permissions in order for it to work.
IOW, an ID10T problem.
It works fine now.
