Powershell Remoting to Exchange: Set-Casmailbox Does Not Have Property Activesyncblockeddeviceids

I am trying to set up a service that disables a user's exchange access by remote powershell to the exchange server and executing like so:

    Set-CASMailbox -Identity usern -OwaEnabled $False
    Set-CASMailbox -Identity usern -EwsEnabled $False
    Set-CASMailbox -Identity usern -EcpEnabled $False
    Set-CASMailbox -Identity usern -MapiEnabled $False
    Set-CASMailbox -Identity usern -MapiBlockOutlookRpcHttp $True
    Set-CASMailbox -Identity usern -EwsAllowMacOutlook $False
    Set-CASMailbox -Identity usern -EwsAllowOutlook $False
//THIS ONE FAILS:
    Set-CASMailbox -Identity usern -ActiveSyncBlockedDeviceIDs "USERSDEVICEID"

ERROR: A parameter cannot be found that matches parameter name 'ActiveSyncBlockedDeviceIDs'.

when I do a Get-Command, from the exchange server itself, it does show ActiveSyncBlockedDeviceIDs in the list of parameters that Set-CASMailbox accepts, however when i do a Get-Command from my c# code on the remote server, it DOES NOT show ActiveSyncBlockedDeviceIDs in the list of parameters!!! am I missing something? is the Set-CASMailbox commandlet different between the one that runs on the server and the one that is exposed remotely? or is this field not supported? (or any other tree I should bark up to get this to happen via a wcf service that is not executing on the exchange server?)

my C# code to execute this from the remote server is like so: (try... blocks,etc removed)

  WSManConnectionInfo connectionInfo = new WSManConnectionInfo(
    new Uri("http://" + server + "/Powershell/Microsoft.Exchange"),
    "",
    credential);

      Runspace runspace = RunspaceFactory.CreateRunspace(connectionInfo);

      PowerShell ps = PowerShell.Create();
      ps.Runspace = runspace;

      //none of these seem to make any difference if i add them or not.
      //ps.Commands.AddScript(@"Import-Module 'C:\Program Files\Microsoft\Exchange Server\V14\bin\RemoteExchange.ps1'");
      //ps.Commands.AddScript(@"Add-PSSnapin Microsoft.Exchange.Management.PowerShell.E2010");
      ps.Commands.AddScript(@"Get-Command");

      runspace.Open();
      var psResult = ps.Invoke();

      //iterate through and find parameters for Set-CASMailbox
      foreach (var res in psResult) {
        if (res.Members["Name"].Value.ToString()=="Set-CASMailbox") {
           foreach (var mem in res.Members) {
            if (mem.Name == "ParameterSets") {
              Console.WriteLine(mem.Value);
              break;
            }
          }
        }
      }

Outputs list or parameters:

(ActiveSyncBlockedDeviceIDs is not there, nor is ActiveSyncEnabledDeviceIDs for that matter)

[-Identity] <MailboxIdParameter> 
[-ActiveSyncDebugLogging <Nullable`1>] 
[-ActiveSyncEnabled] 
[-ActiveSyncMailboxPolicy <MailboxPolicyIdParameter>] 
[-DisplayName <String>] 
[-DomainController <Fqdn>] 
[-ECPEnabled] 
[-EmailAddresses <ProxyAddressCollection>] 
[-EwsAllowEntourage <Nullable`1>] 
[-EwsAllowList <MultiValuedProperty`1>] 
[-EwsAllowMacOutlook <Nullable`1>] 
[-EwsAllowOutlook <Nullable`1>] 
[-EwsApplicationAccessPolicy <Nullable`1>] 
[-EwsBlockList <MultiValuedProperty`1>] 
[-EwsEnabled <Nullable`1>] 
[-HasActiveSyncDevicePartnership] 
[-IgnoreDefaultScope] 
[-ImapEnabled] 
[-ImapEnableExactRFC822Size] 
[-ImapMessagesRetrievalMimeFormat <MimeTextFormat>] 
[-ImapSuppressReadReceipt] 
[-ImapUseProtocolDefaults] 
[-MAPIBlockOutlookNonCachedMode] 
[-MAPIBlockOutlookRpcHttp] 
[-MAPIBlockOutlookVersions <String>] 
[-MAPIEnabled] 
[-Name <String>] 
[-OWAEnabled] 
[-OwaMailboxPolicy <MailboxPolicyIdParameter>] 
[-PopEnabled] 
[-PopEnableExactRFC822Size] 
[-PopMessagesRetrievalMimeFormat <MimeTextFormat>] 
[-PopSuppressReadReceipt] 
[-PopUseProtocolDefaults] 
[-PrimarySmtpAddress <SmtpAddress>] 
[-SamAccountName <String>] 
[-ShowGalAsDefaultView] 
[-Verbose] 
[-Debug] 
[-ErrorAction <ActionPreference>] 
[-WarningAction <ActionPreference>] 
[-ErrorVariable <String>] 
[-WarningVariable <String>] 
[-OutVariable <String>] 
[-OutBuffer <Int32>] 
[-WhatIf] 
[-Confirm]