can any tell me what is the error?

VisitBritain.UTSv_ProductTypeAvailRQ x=null;
            x= new VisitBritain.UTSv_ProductTypeAvailRQ ();

            x.AvailRequestSegments [0].TPA_Extensions.SearchCriteria.ProviderID_List[0]="11163";
            x.AvailRequestSegments [0].StayDateRange.StartDateWindow.EarliestDate="15-september-2006";
            x.AvailRequestSegments [0].StayDateRange.EndDateWindow.EarliestDate="17-september-2006";

            x.AvailRequestSegments [0].ConsumerCandidates[0].ConsumerCounts.ConsumerCount[0].Count="2";
            x.AvailRequestSegments [0].ConsumerCandidates[0].ConsumerCounts.ConsumerCount[0].Count="2";


stack trace

NullReferenceException: Object reference not set to an instance of an object.]
   TestHcgWebService.WebForm1.Page_Load(Object sender, EventArgs e) in c:\inetpub\wwwroot\testhcgwebservice\webform1.aspx .cs:26
   System.Web.UI.Control.OnLoad(EventArgs e) +67
   System.Web.UI.Control.LoadRecursive() +35
   System.Web.UI.Page.ProcessRequestMain() +731