title: ComboBox wpf not item not being selected
body: <p>I am trying to bind a combo box to a list of objects, and it works great, besides the selected value, am I missing somethign?</p>
  
  <pre><code>&lt;ComboBox ItemsSource="{Binding OrderInfoVm.AllCountries}"
            SelectedValuePath="country_code" DisplayMemberPath="country_name" 
            SelectedValue="{Binding OrderInfoVm.BillingCountry}" /&gt;
  </code></pre>
  
  <p>Basically I want to bind value to country codes and set the selected value to the country code bound to OrderInfoVm.BillingCountry (which implements INotifyPropertyChanged)</p>
  
  <p>Initially when the control loads selected value is empty, but on click BillingCountry is populated. Selected value does not seem to change. How can I remedy that?</p>