title: WPF - Cannot retrieve value using the binding and no valid fallback value exists
body: <p>I'm getting a LOT of binding errors in which they all have in common that the binding is something like:</p>
  
  <pre><code>   Text="{Binding MiddleParent.Child}"
  </code></pre>
  
  <p>The errors are saying that the <code>dataitem</code> is null, however my application runs find and the data is there besides the slow performance bc of all the binding error logging going on. This is all happening inside of a <code>datagrid</code>. So for example if my data grid's itemsource is a collection of (<code>MainParent</code>) and inside the <code>datagridcolumn</code> I bind <code>DisplayMemberBinding</code> to: <code>Car.FullName</code>, then in output I get all kind of binding errors. Is this due to lazy loading? How can I fix this. So basically the binding is <code>User.Car.FullName</code>. An example setup is as follows:</p>
  
  <pre><code> &lt;datagrid itemsSource="{Binding Users}"&gt;
        &lt;datagrid.columns&gt;
           &lt;DataGridColumn DisplayMemberBinding="{Binding Car.FullName}" //Throws binding error
           &lt;DataGridColumn DisplayMemberBinding="{Binding Age}" //Does NOT Throw binding error
        &lt;/datagrid.columns&gt;
   &lt;/datagrid&gt;
  
  
  
    System.Windows.Data Information: 10 : Cannot retrieve value using the binding and no valid fallback value exists; using default instead.
  </code></pre>
  
  <p>I have tried setting <code>Fallbackvalue</code> and <code>TargetNullValue</code> and both do not work.
  NOTE: Once app is all loaded, datagrid IS showing the value for Car.FullName, weird I know.</p>