Jeanae on "[Plugin: WordPress MU Domain Mapping] Primary mapping problem"

We have eliminated the redirect from http://www.studyfoundation.ch to http://www.studienstiftung.ch/en. The mapping seems to work now correctly. But I can't access the subpages of the site. E.g. http://www.studyfoundation.ch/partners (previously http://www.studienstiftung.ch/en/partners) goes to "Not Found The requested URL /partners/ was not found on this server."
What can causing this?
Beste regards Jean