WPF Resource Dictionaries Path Problem with ActiveX

My Resource Dictionary in WPF:

<Window.Resources>
    <ResourceDictionary x:Name="ResDic">
        <ResourceDictionary.MergedDictionaries>
            <ResourceDictionary x:Name="dictionary" Source="pack://application:,,,/ProductSelect;component/Loc/ProductSelect.en-US.xaml" ></ResourceDictionary>
        </ResourceDictionary.MergedDictionaries>

This Program works when I start with Visual Studio and as Exe from my folder. But when I start this exe as activex exe from Teststand I am getting an error in InitializeComponent(). I found that this error is caused by the source in line 4 (code above). Exception:

System.IO.IOException: Cannot locate resource 'loc/productselect.en-us.xaml' 

The problem here is, when I start the exe from Teststand it takes another path as working directory for the search after loc/productselect.en-us.xaml but it should take the path from the exe. When I use an absolute path here it works but I don't want an absolute path.

The error from Teststand

FusionLog Output: The Teststand path is of course wrong, i want the path from the exe:

LOG: Attempting download of new URL file:///C:/Program Files (x86)/National Instruments/TestStand 2013/BIN/ProductSelect.DLL.
LOG: Attempting download of new URL file:///C:/Program Files (x86)/National Instruments/TestStand 2013/BIN/ProductSelect/ProductSelect.DLL.
LOG: Attempting download of new URL file:///C:/Program Files (x86)/National Instruments/TestStand 2013/BIN/ProductSelect.EXE.
LOG: Attempting download of new URL file:///C:/Program Files (x86)/National Instruments/TestStand 2013/BIN/ProductSelect/ProductSelect.EXE.

Any ideas?

My Project structure