For those who see the actual PHP code when attempting to include dZip.inc.php, change the opening line in dZip.inc.php from "<?" to "<?php".
On my server, I disallow short_open_tag, so PHP files that begin with <? are not parsed, and the raw file contents are output to the browser.
The use of short-tags is discouraged in most corners of the Internet, for the reason I cited above (it can expose source code when the server is configured not to allow short-tags). Further, code should be written with maximum portability, and using the full PHP tag format (e.g., <?php) always functions as expected, regardless of the short_open_tag directive's value.