Hi, I have an issue trying to implement cascading comboboxes on Silverlight 3. I have two comboboxes:

• Product Type
• Sub Cathegory

The user need to select the Product type, and based on his selection, the second combobox must load the sub cathegories.

Binding the first combobox is a piece of cake:

<ComboBox x:Name="cmbProductType" Margin="11,2,8,5" MaxDropDownHeight="100" Grid.Column="1 />

cmbProductType.ItemsSource = objFactory.ProductTypes;
objFactory.Load(objFactory.GetProductTypesQuery());

My issue is trying to load the second combobox based on the first seleccion. I tryied to implement the SelectionChanged event on the first combobox, but it didn't worked for me:

private void cmbProductType_SelectionChanged(object sender, System.Windows.Controls.SelectionChangedEventArgs e)
    {
        FactoryDS objFactory = new FactoryDS();
        cmbSubCat.ItemsSource = objFactMetas.Campos;
        objFactory.Load(objFactory.GetSubCathegoryQuery(((SybCathegroy)cmbProductType.SelectedItem).Id));
    }

How should I do this? (I'm new on Silverlight). thanks in advance.