performance chat issue vcenter 6.0 - get - powershell

After upgrading to vcenter 6.0

through gui vcenter i am able to fetch the cluster wise data. but when i use powershell below commned no valus are showing ..its returning blank

Get-Stat -Entity ($cluster)-start (get-date).AddDays(-1) -Finish (Get-Date)-MaxSamples 10000 -stat cpu.usage.average

PS C:\> Get-Stat -Entity ($cluster)-start (get-date).AddDays(-1) -Finish (Get-Date)-MaxSamples 10000 -stat cpu.usage.average | Measure-Object -Property value -Average -Maximum -Minimum

PS C:\>

is any counters has been updated in 6.0