[plugin: Wp-O-Matic] server set cron jobs don’t work.

When i set the cron job for wp-o-matic in my direct admin, it doesn’t work. I set it again to run every 5 minutes; a while later it still hasn’t even run 1 time. When i run the cron.php in a browser it works perfectly fine. I can see this works by looking at the log file of wp-o-matic.
When i run the cron in my browser, it says:
04/17 10:17:44 — Running cron job
When i run the cron every 5 minutes from my server it doesn’t log anything so it doesn’t run the cron. How is this possible? What do i do? Other cron jobs ive set for other scripts on my server all run without any problems except for the wp-o-matic one.
This plugin is really causing me headaches..