Thread:Extension talk:Access Control Panel/Help in the privilegie management/reply (3)

The access control extension is designed for coarse-grained access control, i.e. to control entire groups of pages, not individual pages. If you need to control individual pages then I suggest you look at other extensions.

If a member of group A is able to edit pages of group B then there should be somewhere a privilege setting giving group A edit access to pages of group B. Please check the entire list of privileges for all settings involving A and B. Also make sure that namespaces A and B actually exist.