server: C:\Program Files\Microsoft SDKs\Silverlight\v5.0\Libraries\Server\System.ServiceModel.PollingDuplex.dll
client: C:\Program Files\Microsoft SDKs\Silverlight\v5.0\Libraries\Server\System.ServiceModel.PollingDuplex.dll
http://social.msdn.microsoft.com/Forums/silverlight/en-US/d79a3e95-2980-402b-94c7-bcaf15de847e/missing-assembly-systemservicemodelpollingduplexdll