Some hosts have PHP in a different path than our pre-defined cron command. So contact your host regarding the php command path.

Also make sure the cron is running every 20 minutes. The common mistake is setting the cron to 20 minutes instead of */20 (running every 20 minutes)

To make sure its not a script error, run http://YourInfiniteWPURL/cron.php in your browser. If the cron notification disappears after you run them manually, its 100% certain that the cron command was not executed.