Fatal Error on JToolBarHelper

I was developing an administrator component when I experienced this problem:

Fatal error: main() [function.require]: Failed opening required '' (include_path='.;c:\php4\pear') in \site\administrator\components\com_partnercafe\toolbar.partnercafe.php on line 4

The solution, check the filenames of your files. Make sure that you have followed the correct naming convention. On my case, I missed the 'n' on the toolbar.partnercafe.html.php file. Tsk tsk tsk. That's a lesson learned. :)