Could not call Lync Server 2013 Powershell cmdlets from C#

Hi all:

   I made a test programe that run Lync 2013 cmdlet from C#, but failed, the error as following:

   system.management.automation.commandnotfoundexception

   at System.Management.Automation.CommandDiscovery.LookupCommandProcessor(String commandName, CommandOrigin commandOrigin, Nullable`1 useLocalScope)

   at System.Management.Automation.ExecutionContext.CreateCommand(String command)

...

  The code is same as the demo code in MS site as following and the same code could run in Lync 2010 environment:

   http://msdn.microsoft.com/en-us/library/lync/hh364912.aspx

using System;using System.Collections.ObjectModel;using System.Management.Automation;using System.Management.Automation.Runspaces;namespace Microsoft.Rtc.Collaboration.Sample.ApplicationActivation
{class Program
  {staticvoid Main(string[] args)
    {// Get the operating environment to run commands.
      InitialSessionState iss = InitialSessionState.CreateDefault();
      iss.ImportPSModule(new[] { "Lync" });using (Runspace myRunSpace = RunspaceFactory.CreateRunspace(iss))
      {
        myRunSpace.Open();// Execute the Get-CsTrustedApplication cmdlet.using (System.Management.Automation.PowerShell powershell = System.Management.Automation.PowerShell.Create())
        {
          powershell.Runspace = myRunSpace;
          powershell.AddCommand("Get-CsTrustedApplication");

          Collection<PSObject> results = null;
          Collection<ErrorRecord> errors = null;try
          {
            results = powershell.Invoke();
            errors = powershell.Streams.Error.ReadAll();
          }catch (Exception ex)
          {// An error occurred running the cmdlets.// TODO (Left to the reader): Error handling code.throw;
          }if (errors.Count != 0)
          {// Errors were reported by the cmdlets.// TODO (Left to the reader): Error handling code.
          }foreach (PSObject result in results)
          {
            Console.WriteLine("Identity\t: "+ result.Members["Identity"].Value);
            Console.WriteLine("ApplicationId\t: "+ result.Members["ApplicationId"].Value);
          }
          Console.WriteLine("Press any key to exit...");
          Console.ReadKey();
        }
      }
    }
  }
}
  Could anyone help with this issue?
Thanks