You can't have 2.6.1 and have that message. Although the Notifications page says you do. That's strange. I can only conclude that *something* happened when this broke. What was it? You might be better making some enquiries.
What does "it doesn't work" look like? What happens if you run
/usr/bin/php /usr/local/onlinecourse/admin/cron.php
...directly on the command line?