Issue with Get-LogonStatistics in Exchange 2013

Hi all,

I run into an issue with the Get-LogonStatistics cmdlet. The error says:

Cannot find LogonStatistics objects from the root 'DB1'. Please make sure that you specified the correct search root and that you have the correct permissions to perform the search.
    + CategoryInfo          : NotSpecified: (:) [Get-LogonStatistics], MapiOperationException
    + FullyQualifiedErrorId : B3D0201A,Microsoft.Exchange.Management.MapiTasks.GetLogonStatistics
    + PSComputerName        : mb1.ex2013.test

I run that cmdlet as a member of the OrganizationAdmin rolegroup.

Any ideas?

Thanks in advance!