Permission error in Nagios

I’m having problems with Nagios. I added several services, but three of them are not giving me permission to view. The following message appears:

It appears as though you do not have permission to view information for this service…

If you believe this is an error, check the HTTP server authentication requirements for accessing this CGI
and check the authorization options in your CGI configuration file.

Anyone can help?

P.S.: Sorry for my english.

are the same contacts assigned as the other services?