I have a ComboBox:

<ComboBox Name="iComponentFieldComboBox" SelectedIndex="{Binding ComponentFieldSelectedIndex, Mode=TwoWay}" Height="23" Margin="132,0,280,38" VerticalAlignment="Bottom">
    <ComboBoxItem Name="item1">item1</ComboBoxItem>
    <ComboBoxItem Name="item2">item2</ComboBoxItem>
    <ComboBoxItem Name="item3">item3</ComboBoxItem>
</ComboBox>

When I start my WPF and set the ComponentFieldSelectedIndex property of my ViewModel in my code, nothing happens. But after I have selected an item in the combobox, then suddenly setting ComponentFieldSelectedIndex does work.

for example:

• start app.
• click button that sets ComponentFieldSelectedIndex to 1.
• selected item doesn't change to item2.
• select item3 in combo box.
• click button that sets ComponentFieldSelectedIndex to 1.
• selected item does change to item2.

Does anyone have an idea what could be causing this?