如何在WPF ComboBox中显示初始值

XAML Code

<ComboBox Height="23" Margin="69,105,111,0" Name="comboBox1" VerticalAlignment="Top" ItemsSource="{Binding StoreTypeTable}" DisplayMemberPath="StoreTypeName" SelectedValuePath="StoreTypeName"  IsSynchronizedWithCurrentItem="True" SelectedIndex="0"/>
<ComboBox Height="23" Margin="69,10