Chances are you weren't actually pinging iTunes with Podpress. Podpress never reported whether the ping was successful or not.
If you take a look at the changelog for Podpress, the ping iTunes functionality was temporary disabled for some reason and instead replaced with a link that you must click manually to ping iTunes. So if you were using Podpress 6.7 or newer, you were not pinging iTunes. I just took a look at the latest version of Podpress v8.8 source code and it does not ping iTunes.
You can manually ping iTunes yourself by replacing the XXXXXXXX with your iTunes podcast ID and entering the final URL into your web browser.
https://phobos.apple.com/WebObjects/MZFinance.woa/wa/pingPodcast?id=XXXXXXXXThe URL that needs to be pinged on iTunes is a https:// URL. In order to access a secure https:// URL, you must have openssl or curl installed in PHP.
The latest versions of Blubrry Powerpress can ping iTunes using either libraries (openssl or curl). If you can add php_curl or php_openssl to your server then you should not have any problems pinging iTunes.
Do you have root user access to your server? If you do not, you may need to contact your ISP and request that they add this support for you.
Thanks,
Angelo