Thanks for your help. Neither of those things were the issue. I did get it working finally. I had tried a few months ago to get SEF url's working without success. I noticed that I had a .htaccess and a htaccess.txt file. I downloaded a copy of the txt file then deleted it. I couldn't access .htaccess from the Admin backend so I used my cpanel. I tried to delete .htaccess and then I uploaded the htaccess.txt file and renamed it .htaccess; then I commented and uncommented the appropriate lines and it finally worked. Now there is only the .htaccess file. I don't even know how the original .htaccess file got there although I'm pretty sure it had the same exact rewrite rules.

I have tried to follow the configuration Checklist

1. .htaccess exists
2. 3rd party section rules are uncommented
3. Joomla is in my root directory
4. I turn on SEF in Global configuration
5. JoomSEF is on

yet I get the 404 error message that the url is not found on the server?

What could I be doing wrong?