MyBB Community Forums

I have a forum that is world readable but only administrators can post.

If I am a primary member of the Administrators group but have sub-groups as well I cannot post in this forum.

Are you sure the permissions are set correctly? Ensure that "administrators" have full permission on the forum.

They do have full permissions.

When I removed my "regular member" secondary mask I was able to post.

You need to explicitly set the forum permissions for all usergroups in that forum

I was under the impression that the permission system was aggregate.

Is this incorrect?