http://developers.de/blogs/damir_dobric/archive/2010/04/22/unauthorizedaccessexception-invalid-cross-thread-access.aspxWhen working with WCF DataServices in Silverlight 3 your callback methods have been executed on the UI-thread. Here is one example which works in Silverlight 3.0. &#160; &#160;&#160; private void onOperationCompleted( IAsyncResult result) &#160;&#160;enCommunityServer 2008 SP1 (Build: 30619.63)http://developers.de/blogs/damir_dobric/archive/2010/04/22/unauthorizedaccessexception-invalid-cross-thread-access.aspx#12627Thu, 03 Jun 2010 06:56:09 GMT7e491611-45ad-4dae-a68f-c4cb64439510:12627Klin<p>Cool</p> <p>it&#39;s works!!!</p> <div style="clear:both;"></div><img src="http://developers.de/aggbug.aspx?PostID=12627" width="1" height="1">