Error when I want to use a map service

Hi,

I am having problems when I try to use map services from a server connect as a user, I can not add the service. When connect as an administrator, I can load the data. The service is publish with no security, so I do not understand why I can not load it as a user, help please?.

BTW, the problem occurs when accessing the server from internet, local there is no problem.

Regards,
Manuel