Cronjob error message: curl: (6) Couldn't resolve host '[Site name]'

Hi, Gentlemen!

I have an issue here. I´ve tried to insert this code in ssh:

*/5 * * * * curl " http://3drevolution/index.php?option=com_cobalt& ;task=cron.checkIn&secret=secretkey"

But the served answered with that:

curl: (6) Couldn't resolve host '3drevolution'

Could you please tell me what is going wrong?

Thanks in advance!