How to make sure you dont get WCF Faulted State Exception?

Question

I am getting this exception

"The communication object, System.ServiceModel.Channels.ServiceChannel, cannot be used for communication because it is in the Faulted state"

The WCF service uses the default wsHttpBinding. I am using WCF in the following way wherever I am using it -

using (var proxy = new CAGDashboardServiceClient())
            {
                proxy.Open();
                var result = proxy.GetSiteForRegion(ddlRegions.SelectedValue);
                ddlSites.DataSource = result;
                ddlSites.DataBind();
                proxy.Close();
            }

The error line shown in the message seems to be after last proxy.close. Not sure what is going on. I am launching the service from within visual studio 08.

Here is the trace information

The communication object, System.ServiceModel.Channels.ServiceChannel, cannot be used for communication because it is in the Faulted state.

Server stack trace: 
  at System.ServiceModel.Channels.CommunicationObject.Close(TimeSpan timeout)

Exception rethrown at [0]: 
  at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
  at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
  at System.ServiceModel.ICommunicationObject.Close(TimeSpan timeout)
  at System.ServiceModel.ClientBase`1.System.ServiceModel.ICommunicationObject.Close(TimeSpan timeout)
  at System.ServiceModel.ClientBase`1.Close()
  at System.ServiceModel.ClientBase`1.System.IDisposable.Dispose()
  at CAGDashboard.UserControls.ucVolunteerCRUDGrid.ddlRegions_SelectedIndexChanged(Object sender, EventArgs e) in C:\Documents and Settings\rballalx\My Documents\Visual Studio 2008\Projects\DashboardCAG\CAGDashboard\UserControls\ucVolunteerCRUDGrid.ascx.cs:line 81
  at System.Web.UI.WebControls.ListControl.OnSelectedIndexChanged(EventArgs e)
  at System.Web.UI.WebControls.DropDownList.RaisePostDataChangedEvent()
  at System.Web.UI.WebControls.DropDownList.System.Web.UI.IPostBackDataHandler.RaisePostDataChangedEvent()
  at System.Web.UI.Page.RaiseChangedEvents()
  at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

Answer 1

You should avoid putting client proxies in 'using' blocks, see

http://msdn.microsoft.com/en-us/library/aa355056.aspx