NotesSession.AddressBooks == null。有什么想法吗？

Question

在使用某个用户ID初始化NotesSession之后，会话被初始化，但属性NotesSession.AddressBooks变为NULL。它仅适用于某些用户ID，但我找不到任何原因，这些用户有什么问题。

NotesSession session = new NotesSession();
                session.Initialize(password);
if (session.AddressBooks != null)
                    {
                        Console.WriteLine(string.Format(CultureInfo.InvariantCulture, "addressBooks Length: {0}", session.AddressBooks.Length));
                        foreach (IDatabase addressBook in session.AddressBooks)
                        {
                            if (addressBook.IsPublicAddressBook)
                            {
                                addressBookInfo.Add(addressBook.FilePath, addressBook.FileName);
                                Console.WriteLine(string.Format(CultureInfo.InvariantCulture, "addressBook.FileName:{0}  ", addressBook.FileName));
                                Console.WriteLine(string.Format(CultureInfo.InvariantCulture, "addressBook.FilePath:{0} ",  addressBook.FilePath));
                                Console.WriteLine();
                            }
                            else
                            {
                                Console.WriteLine(string.Format(CultureInfo.InvariantCulture, "addressBook.IsPublicAddressBook: {0}", addressBook.IsPublicAddressBook));
                                Console.WriteLine(string.Format(CultureInfo.InvariantCulture, "addressBook.FileName: {0}", addressBook.FileName));
                                Console.WriteLine();
                            }
                        }
                    }  

}

任何想法为什么会发生？ 任何想法请帮助