Installation problem

[eluser]skunkbad[/eluser]
I just uploaded my CodeIgniter site, and even though I had it working locally, and in a test folder on the production server, I am getting an error:

[25-May-2009 21:33:44] PHP Warning: require(application/config/constants.php) [<a href='function.require'>function.require</a>]: failed to open stream: No such file or directory in /home/dirbase/public_html/system/codeigniter/CodeIgniter.php on line 52
[25-May-2009 21:33:44] PHP Warning: require(application/config/constants.php) [<a href='function.require'>function.require</a>]: failed to open stream: No such file or directory in /home/dirbase/public_html/system/codeigniter/CodeIgniter.php on line 52
[25-May-2009 21:33:44] PHP Fatal error: require() [<a href='function.require'>function.require</a>]: Failed opening required 'application/config/constants.php' (include_path='.:/usr/lib/php:/usr/local/lib/php:/home/dirbase/php') in /home/dirbase/public_html/system/codeigniter/CodeIgniter.php on line 52

The constants file is there... so I'm not sure what to do. When I try to load the home page, the screen is blank, and the header says 500 Server Error.