Get-RDUserSession in Powershell in pssession

I type command in Powershell Get-RDUserSession. I get all connecting user in terminal serwer.

When I type this command in pssession I get error:

Cannot index into a null array.
At C:\windows\system32\windowspowershell\v1.0\Modules\RemoteDesktop\Utility.psm1:54 char:9
+     if ($_script_resource[$Id])
+         ~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : NullArray

Server is Windows 2012 R2. PSsession i established from Windows 8.1