InitializeComponent exception

I get an exception whenever I try to use OxyPlot in a UserControl (VS extension), I see that OxyPlot.dll and OxyPlot.Wpf.dll exist in the deployment location, and the XAML parses fine in the designer.

XAML:
<usercontrol x:class="GraphicalDebugging.PlotWatchControl"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:oxy="clr-namespace:OxyPlot.Wpf;assembly=OxyPlot.Wpf" 
             mc:ignorable="d"
             d:designheight="300" d:designwidth="800">
  <grid>
    <oxy:plotview model="{Binding MyModel}"></oxy:plotview>
  </grid>
</usercontrol>

and in my UserControl class I got:

using OxyPlot;
using OxyPlot.Wpf;
namespace MyNS {
    public partial class MyControl : Usercontrol
    {
        ...
        public PlotModel MyModel { get; private set; }
    }
} 

The exception I get is:

System.Windows.Markup.XamlParseException occurred
  HResult=0x80131501
  Message=Could not load file or assembly 'OxyPlot.Wpf, PublicKeyToken=75e952ba404cdbb0' or one of its dependencies. The system cannot find the file specified.
  Source=PresentationFramework
  StackTrace:
   at System.Windows.Markup.WpfXamlLoader.Load(XamlReader xamlReader, IXamlObjectWriterFactory writerFactory, Boolean skipJournaledProperties, Object rootObject, XamlObjectWriterSettings settings, Uri baseUri)
   at System.Windows.Markup.WpfXamlLoader.LoadBaml(XamlReader xamlReader, Boolean skipJournaledProperties, Object rootObject, XamlAccessLevel accessLevel, Uri baseUri)
   at System.Windows.Markup.XamlReader.LoadBaml(Stream stream, ParserContext parserContext, Object parent, Boolean closeStream)
   at System.Windows.Application.LoadComponent(Object component, Uri resourceLocator)
   at GraphicalDebugging.PlotWatchControl.InitializeComponent() in C:\code\git\temp\graphical-debugging\Visual_Studio_2015\GraphicalDebugging\PlotWatchControl.xaml:line 1
   at GraphicalDebugging.PlotWatchControl..ctor() in C:\code\git\temp\graphical-debugging\Visual_Studio_2015\GraphicalDebugging\PlotWatchControl.xaml.cs:line 29
   at GraphicalDebugging.PlotWatch..ctor() in C:\code\git\temp\graphical-debugging\Visual_Studio_2015\GraphicalDebugging\PlotWatch.cs:line 37
Inner Exception 1:
FileNotFoundException: Could not load file or assembly 'OxyPlot.Wpf, PublicKeyToken=75e952ba404cdbb0' or one of its dependencies. The system cannot find the file specified.

I've installed OxyPlot.Wpf via Nuget. Ideas ??