can not sort datagrid

[ForamParikh]

I tried this example http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#SpatialQuery in this example sorting is working perfectly fine but in my example sorting is not working.I am using join between tables in my service.below is

<sdk:DataGrid x:Name="QueryDetailsDataGrid" Grid.Row="1" Width="Auto" Height="170"
                                AutoGenerateColumns="False" CanUserSortColumns="True"
                                VerticalAlignment="Bottom" HorizontalAlignment="Left"
                                HeadersVisibility="Column" HorizontalScrollBarVisibility="Hidden"
                               SelectionChanged="QueryDetailsDataGrid_SelectionChanged"
                             
                              >
            <sdk:DataGrid.Columns>
                <sdk:DataGridTextColumn CanUserSort="True" CanUserReorder="True"   Binding="{Binding Attributes[GIC4.DBO.PROJECT_INFO.PROJ_NAME]}" Header="Name"/>
                <sdk:DataGridTextColumn CanUserSort="True"  Binding="{Binding Attributes[GIC4.DBO.PROJECT_INFO.PROJSTAT]}" Header="Status"/>              
               
              
            </sdk:DataGrid.Columns>
        </sdk:DataGrid>

and here is code behind

QueryTask queryTask =
               new QueryTask("http://pipelineforthefuture.org/ArcGIS/rest/services/GIC4/polyjoint/MapServer/1");
            queryTask.ExecuteCompleted += QueryTask_ExecuteCompleted;
            queryTask.Failed += QueryTask_Failed;

            Binding resultFeaturesBinding = new Binding("LastResult.Features");
            resultFeaturesBinding.Source = queryTask;
            QueryDetailsDataGrid.SetBinding(DataGrid.ItemsSourceProperty, resultFeaturesBinding);

           

            ESRI.ArcGIS.Client.Tasks.Query query = new ESRI.ArcGIS.Client.Tasks.Query();
            query.Where = "GIC4.DBO.PROJECT_INFO.PROJECT_ID > 275";

            query.OutFields.Add("*");
            queryTask.ExecuteAsync(query);


also in my service i used join and to get features in attribute i have to write the whole name like GIC4.DBO.PROJECT_INFO.PROJECT_ID how to change column name?i just want to write project_id and it should bind that value please look at my service and let me know where i am wrong my grid is binding correctly but sort function is not working.

Please help,

Thanks
Foram
Please help,

[JenniferNery]

That's right, this SDK sample does not sort either: http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#QueryWithoutMap. This, howeverhttp://help.arcgis.com/en/webapi/silverlight/samples/start.htm#FeatureDataGrid. Try using FeatureDataGrid instead of regular DataGrid.