At this stage, it's difficult to guess where the issue is. I suggest a debugging scenario in 2 steps: 1) Look at error message returned by layer initializationa) hook up an handler to layer event 'InitializationFailed' by adding this in XAML: InitializationFailed="Layer_InitializationFailed"b) display the error with this code:
private void Layer_InitializationFailed(object sender, EventArgs e)
{
Layer layer = sender as Layer;
MessageBox.Show(layer.InitializationFailure.Message);
}
2) If then no idea about the problem, use an HTTP traffic sniffer such as fiddler to see the request your silverlight application is making. Note that, even if your application and your services are on the same server, you need a cross domain policy file if you are not using the same domain path (which is the case while debugging).