Mybook Essential 2TB email backups

Hi I just installed my new My Book Essential 2TB drive updated the firmware, and updated the drivers, I am noticing some strange behavior with my backup, My mail is not backing up, the backup software is as follows , Mial in pc is in Yellow, Mail on Drive is in Grey, system files are allso grey. Files not backed up sais 2 files failed to backup.

Outlook.pst 370.08mb File Pending Backup.

Archive.pst The process can not access the file because another

Any help appreciated, I really need the security of having all my emails ect backed up for work purposes.

Make sure the software is updated as well

can you please confirm what firmware and software version you have?