private void ArcGISDynamicMapServiceLayer_Initialized(object sender, EventArgs e)
{
ESRI.ArcGIS.Client.ArcGISDynamicMapServiceLayer dynamicServiceLayer =
sender as ESRI.ArcGIS.Client.ArcGISDynamicMapServiceLayer;
if (dynamicServiceLayer.VisibleLayers == null)
dynamicServiceLayer.VisibleLayers = GetDefaultVisibleLayers(dynamicServiceLayer);
}