I am trying to create a user and a group for this user which limits this user to see nothing else than Sales Application --> Customers and among all customers only special ones. I was able to let him see exactly the required customers by creating a corresponding record rule. So far, so good... But when this user is logged in, partners can not be saved after edit or create. The following error occurs:

Access Denied The requested operation cannot be completed due to security restrictions. Please contact your system administrator. (Document type: Partner, Operation: read)

Please see at attached picture, which access rights i have already tried to achieve write access with. Can anybody explain me which rights are missing to get write access to the desired range of partner data? My Odoo version is v7.