title: DevExpress 15.1 WPF - Apply custom theme
body: <p>I have trouble with applying custom theme to DevExpress 15.1 WPF application.</p>
  
  <p>I have done steps:</p>
  
  <ul>
  <li>Create new Theme based on Metropolis Light with DevExpress Theme Editor(newest version)</li>
  <li>Compile it</li>
  <li>Add reference to compiled dll in my application</li>
  <li><p>Add this before <code>InitializeComponent()</code> in my MainWindow:</p>
  
  <p><code>Theme theme = new Theme("MyTheme", "DevExpress.Xpf.Themes.MyTheme.v15.1");
  theme.AssemblyName = "DevExpress.Xpf.Themes.MyTheme.v15.1";
  Theme.RegisterTheme(theme);
  ThemeManager.SetTheme(this, theme);</code></p></li>
  </ul>
  
  <p>The result is exception:</p>
  
  <pre><code>An exception of type 'System.Reflection.TargetInvocationException' occurred in System.Xaml.dll but was not handled in user code
  
  Additional information: Exception has been thrown by the target of an invocation
  </code></pre>
  
  <p>with inner exception</p>
  
  <pre><code>{"Object reference not set to an instance of an object."}
  
  at DevExpress.Xpf.Core.ThemedElementsDictionary.GetAssemblyFullName(Object key)
  at DevExpress.Xpf.Core.ThemedElementsDictionary.RegisterThemeType(String themeName, String fullName, Object key)
  </code></pre>
  
  <p>Do you have idea what I'm doing wrong? Maybe it has changed in 15.1?</p>