title: Xceed Wpf Toolkit works in code but not designer
body: <p>I am hoping this problem is just me being unfamiliar with WPF.
  I am able to use the XCeed toolkit in code with no problems:</p>
  
  <pre><code>        DateTimePicker dtp = new DateTimePicker();
          dtp.HorizontalAlignment = HorizontalAlignment.Left;
          dtp.VerticalAlignment = VerticalAlignment.Top;
          dtp.Width = 200;
          dtp.Height = 24;
          dtp.Margin = new Thickness(50, 10, 0, 0);
          dtp.FontStyle = FontStyles.Normal;
          InBoundGrid.Children.Add(dtp);
  </code></pre>
  
  <p>This works fine in my form.
  But I cannot figure out how do get it working in the designer:
  I've added:</p>
  
  <pre><code>xmlns:wpfx="http://schemas.xceed.com/wpf/xaml/toolkit"
  </code></pre>
  
  <p>to the Window definition.
  It shows fine in "intellisense"
  So when I start typing wpfx:... the DateTimePicker contol shows in the intellisense menu.</p>
  
  <p>However:</p>
  
  <pre><code>         &lt;wpfx:DateTimePicker
              HorizontalAlignment="Left"
              VerticalAlignment="Top"
              Width="200"
              Height="24"
              Margin="50,10,0,0"
              FontWeight="Normal"
           /&gt;
  </code></pre>
  
  <p>comes back with the error:</p>
  
  <p>"The name "DateTimePicker" does not exist in the namespace <a href="http://schemas.xceed.com/wpf/xaml/toolkit" rel="nofollow">http://schemas.xceed.com/wpf/xaml/toolkit</a>"</p>
  
  <p>All the other Xceed controls show the same error in xaml designer.
  Also, please note I do not want to try the Nuget installer.
  (I tried but got the same error anyway)
  I would like to keep my code base as small as possible.</p>
  
  <p>Thanks in advance.</p>