Why can't I access local copy of Notes DB

I have a Notes DB on my workspace where the database file location is on a company server and I can access this database because I am member of a group in the ACL. However, when I make a local copy on my workspace and I attempt to access the database I am given the message "You are not authorised to access that database". Why is this and how do I resolve the access issue? I have checked that the "Enforce a consistent Access Control List across all replicas" is checked in the Advanced tab of the ACL