Dedup showing 0% savings

Hi Everyone,

I enabled dedup on a backup drives used for SQL server backups and left it a couple of days. When I check the folder properties it has the following proeprties:

Size: 418GB

Size on Disk : 140GB

But overall usage on the drive as reported by My Computer has not gone down. File services reports 0% saving.

PS C:\Windows\system32> Get-DedupStatus Y:

FreeSpace    SavedSpace   OptimizedFiles     InPolicyFiles      Volume
---------    ----------   --------------     -------------      ------
13.02 GB     0 B          117                134                Y:

Any ideas?