get-ummailbox error with ex2013

Get-ummailbox
Property AccessTelephoneNumbers can't be set on this object because it requires the object to have version 0.10
(14.0.100.0) or later. The object's current version is 0.1 (8.0.535.0).
    + CategoryInfo          : NotSpecified: (:) [Get-UMMailbox], InvalidObjectOperationException
    + FullyQualifiedErrorId : [Server=EXCH01,RequestId=1b92d7d4-d4dd-41ea-8eb6-3e4e15e1cde5,TimeStamp=6/15/2015 3:5
   1:31 PM] [FailureCategory=Cmdlet-InvalidObjectOperationException] FE250A79,Microsoft.Exchange.Management.Recipient
  Tasks.GetUMMailbox
    + PSComputerName        : exch01.net

not sure why im getting the above error.