Wpf SelectedItem wont work for a Combobox in a ListView

I´ve got a problem with a Combobox in a ListView. I´ve got a class called "Substrate". This class contains an object of a class called "SubstrateType". I want to show the objects of the class "Substrate" in a Listview. Each property of the "Substrate" is presented in the columns of the Listview. For the different "SubstrateType" I want to use a combobox.

In the XAML I tried it like this:

<ComboBox Name="CBType"
          ItemsSource="{Binding ElementName=SettingsSubstrate, Path=TypeList}"
          SelectedItem="{Binding Path=Substrate.SubstrateType}"
          DisplayMemberPath="Description"/>

In the code-behind I got two ObservableCollections. One for all Substrates and one for all possible SubstrateTypes. The combobox displays all SubstrateTypes if you click on it. But the combobox has no selecteditem if you dont select one.

http://i44.开发者_如何学Gotinypic.com/2eakxav.png

Thanks in advance.

I do not know your exact code, but if your ListView rows display objects of type Substrate, then your Binding Path for the SelectedItem should be just SubstrateType because the DataContext of a ListViewItem is already set to the Substrate object:

SelectedItem="{Binding Path=SubstrateType}"

Furthermore, you need to make sure that your SubstrateType instances are actually considered as equal. If the SubstrateType instance in your Substrate object is not exactly the same as the one from the TypeList property, it will not be selected. You can fix that by overriding the Equals(...) method and define your custom comparison for equality.

If this does not work, please provide more code, e.g. the surrounding XAML and the code of Substrate and the code-behind/ViewModel/whatever.