Featurelayer.Update() doesn't request anything from server

[KirkKuykendall]

I want to load some features into a featurelayer, but Fiddler shows no request when featurelayer.Update() is called. Neither UpdateCompleted nor UpdateFailed get fired.

I'm using SelectionOnlyMode.

Is there some way to load a featurelayer with only the features based on a list of ObjectIDs ?

private void button1_Click(object sender, RoutedEventArgs e)
{
    var fLayer = MyMap.Layers["MyFeatureLayer"] as FeatureLayer;
    fLayer.ObjectIDs = new int[] { 1, 2, 3, 4 };
    fLayer.UpdateCompleted += (s, ea) =>
        {
            Debug.Print(fLayer.Graphics.Count.ToString() + " features selected");
        };
    fLayer.UpdateFailed += (s, ea) =>
        {
            Debug.Print("update failed: " + ea.Error.Message);
        };

    fLayer.Update();
}

<esri:Map x:Name="MyMap" Extent="-130,10,-70,60" Grid.Row="1">
    <esri:Map.Layers>
        <esri:ArcGISTiledMapServiceLayer ID="StreetMapLayer"
        Url="http://server.arcgisonline.com/ArcGIS/rest/services/ESRI_StreetMap_World_2D/MapServer"/>
        <esri:FeatureLayer ID="MyFeatureLayer" Mode="SelectionOnly"
        Url="http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Specialty/ESRI_StatesCitiesRivers_USA/MapServer/0" >
        </esri:FeatureLayer>
    </esri:Map.Layers>
</esri:Map>
<Button Content="Button" Click="button1_Click" Height="21" HorizontalAlignment="Left" Margin="58,0,0,0" Name="button1" VerticalAlignment="Top" Width="63" />

Any suggestions would be greatly appreciated, Thanks!

[DominiqueBroux]

Neither UpdateCompleted nor UpdateFailed get fired.
I'm using SelectionOnlyMode.

In SelectionOnlyMode, the graphics are never automatically added by executing the query. The graphics have to be added manually (by a selection or by the API).

The other modes (Snapshot, OnDemand) should work. Did you run into issue with others modes?