Using query OrderByFields

[DonFreeman]

I am trying to use the sample located here http://resources.arcgis.com/en/help/silverlight-api/samples/start.htm#OrderByFieldQuery. But my code

 Query myFinalQuery = new ESRI.ArcGIS.Client.Tasks.Query()
   {
    ReturnGeometry = true,
    Where = "1=1",
    OrderByFields = new List<OrderByField>() { new OrderByField("PLACENAM_3", SortOrder.Ascending) }
   };

produces an error that says "ESRI.Client.Tasks.Query does not have a definition for OrderByFields"

Thoughts to fix? perhaps I need a newer or different reference?

[DominiqueBroux]

Which ArcGIS API version are you using? If I remember well, OrderByFields has been added in version 3.1.

[DonFreeman]

Thanks. I was in 2.4. After upgrading it worked OK.