I have a file named display.inc that includes files in the same directory but I get this warning:
Warning: Failed opening 'string.php' for inclusion (include_path='')
Any Ideas?
Sounds like the file your including isn't found...
Try specifying the exact root for the file, something like
include "/usr/home/username/public_html/string.php";
Better, check your php.ini's include_path setting first.
Best(?), set your include_path using ini_set().