Problem With Dot Net Builder Classes in C# WPF applications

I am trying to use the Matlab DotNetBuilder to use a function I have in matlab in c# but I am having exceptions thrown whenever I try and initialise the matlab class.The code below throws "

An unhandled exception of type 'System.TypeInitializationException' occurred in myProgram.exe Additional information: The type initializer for 'myMatlabNamespace.MatlabClass' threw an exception.

Uncommenting the initialisation of MWArray makes it throw

An unhandled exception of type 'System.BadImageFormatException' occurred in PresentationCore.dll

Additional information: Could not load file or assembly 'MWArray, Version=2.11.1.0, Culture=neutral, PublicKeyToken=xxxxxxxx' or one of its dependencies. An attempt was made to load a program with an incorrect format.

using System;
using MathWorks.MATLAB.NET.Arrays;
using MathWorks.MATLAB.NET.Utility;
using myMatlabNamespace;

namespace WPF
{
    public partial class myMainWindow : Window
    {
        public myMainWindow()
        {
            InitializeComponent();
        }

          private void runMatlabStuffButton_Click(object sender, RoutedEventArgs e)
          { 
              var obj = new MatlabClass();
              MWArray[] fooish = new MWArray[60]; 
          }

      }
  }

Looking at similar questions on MathWorks and other forums it seems like this problem is usually caused by trying to run a 32 bit .NET assembly on a 64 Bit machine but that is not what I an trying to do.I compiled the .NET assembly on the windows 7 X64 matlab 2011b version, targeting .NET 4.0 , and I am running the assembly on VS2012, .NET 4.5, platform X64.So there shouldn't be any compatibility issues.Does anyone know how I can solve this problem? Any help will be greatly appreciated.

Also Note: The matlabClass seems to work just fine when I start a project as a console application and use it over there but it just won't work on my WPF application, this is even though both compile in x64, is there something I have to do to make DotNetBuilder classes work in WPF applications? I even thought there must have been something wrong with my particular WPF project because it's a big project with many classes and all so I tried creating a completely new WPF project then adding the matlab class but it still won't work! Is there something I have to do to make dotNetBuilder classes work on WPF applications? Please help