set SelectedIndex of Combobox in WPF to 0
===

I am binding a Collection at run time to a Combobox and I would like to set the Index after to 0. I could not find a straight answer to what I want.

    _stationNames = new ObservableCollection<string>(_floorUnits.Unit.Select(f => f.Name));
    _stationNames.Insert(0, "All");
    stationsComboBox.ItemsSource = _stationNames;
    stationsComboBox.SelectedIndex = 0;//Doesn;t work

Xaml

    <ComboBox x:Name="stationsComboBox" Grid.Row="1" Grid.Column="1" Text="{Binding Name}"
                      SelectionChanged="StationComboBoxSelectionChanged" VerticalAlignment="Center" Margin="3"
                       SelectedIndex="0"/>