Backup exec 2014 Server 2012(storage) and RDX cartridges not available

Hi,

  Im new to this version of backup exec,  and am in the process of (attempting) to configure some RDX drives as Disk cartridge devices, however  this option is greyed out.  Under configure storage  it shows as "there are no  unconfigured disk cartrige devices on the system".  I've  tried restarting the Backup exec services after inserting the drive and  it shows in  Computer(this pc in server 22012)  as a removeable device,  Why doesn't Symantec recognize it , any tricks to  get this working?

  Thanks