Databinding combobox selected item to settings

I store user specified settings using application settings properties and databinding. It has been working fine, until i want user selected to font for combobox. Databinding between user settings and combobox not working. I want t开发者_JAVA百科o store font family name.

App.XML
<Application.Resources>
    <ResourceDictionary>
        <properties:Settings x:Key="Settings" />
    </ResourceDictionary>               
</Application.Resources>

Window.XML

<ComboBox Name="Families" ItemsSource="{x:Static Fonts.SystemFontFamilies}"
  <!-- This line -->
  SelectedItem="{Binding Source={StaticResource Settings}, Path=Default.Font, Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
              Margin="57,122,199,118">
        <ComboBox.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding}" FontFamily="{Binding}"/>
        </DataTemplate>
        </ComboBox.ItemTemplate>
    </ComboBox>

Settings: font String User Arial

In what way isn't it working? Is an exception thrown, is the project not compiling, or is the setting is not getting saved?

Don't forget that you must expressly save settings once they are modified. For this reason, you might do better to bind to an ICommand that applies and saves the setting, rather than to the setting directly, or add a "save" button that is bound to such a command.

Adding SelectedValuePath="Source" solve this problem.