IE11 - IEventTarget.addEventListener - Can't access to IDOMEvent from a C# test automation tool

I'm facing difficulties to get access to IE events (IDOMEvent) in the context of a Test Automation tool written in C# and running standalone (i.e.: The tool is not an IE plug-in). I can produce the problem with IE11 and web applications enforcing the IE=EDGE compatibility mode via the HEAD meta-information:

  <meta http-equiv="X-UA-Compatible" content="IE=EDGE">

I have created an EventSink class which registers for the "click" events at the body HTML element using the IEventTarget.addEventListener method:

  public class EventSink : IDisposable, IReflect
  {
    private IEventTarget mm_eventTarget;
    bool mm_attached = false;

    public void Attach(IHTMLDocument2 observedDocument)
    {
      mm_eventTarget = observedDocument.body as IEventTarget;
      //mm_eventTarget = observedDocument as IEventTarget;
      if (mm_eventTarget != null)
      {
        mm_eventTarget.addEventListener("click", this, true);     //Registration for click during the "capturing" phase
        mm_attached = true;
      }
    }

    ...
  }

The EventSink class implements the IReflect interface and thus gets called back in its IReflect.InvokeMember method when a mouse click occurs.

  public class EventSink : IDisposable, IReflect
  {
    ...

    object IReflect.InvokeMember(string name, 
                                 BindingFlags invokeAttr, 
                                 Binder binder, 
                                 object target, object[] args, 
                                 ParameterModifier[] modifiers, 
                                 CultureInfo culture, 
                                 string[] namedParameters)
    {
      if ("[DISPID=0]" == name)
      {
        try
        {
          IHTMLElement bodyElement = args[0] as IHTMLElement;

          IDOMEvent domEvent = args[1] as IDOMEvent;                    //<== This works properly - domEvent is not null!
          IHTMLElement element = domEvent.target as IHTMLElement;       //COM Exception here - DISP_E_MEMBERNOTFOUND
        }
        catch (Exception e)
        {
          Console.
        }
      }
      return null;
    }

The IReflect.InvokeMember method receives two arguments as described at:
https://msdn.microsoft.com/en-us/library/ie/ff975245%28v=vs.85%29.aspx?f=255&MSPPError=-2147217396

- The first one is the body HTML element 
- The second one is supposed to be the IDOMEvent

The problem is that the C# class can't access to it. A COM exception occurs as soon as I manipulate the proxy to the DOM Event. Note that casting args[1] to IDomEvent works properly but afterwards all methods are triggering the same error:
==> "Member not found. (Exception from HRESULT: 0x80020003 (DISP_E_MEMBERNOTFOUND))

Here is the IDL definition of the IEventTarget and IDOMEvent interfaces that my project is using:

  [Guid("305104B9-98B5-11CF-BB82-00AA00BDCE0B")]
  [TypeLibType(4160)]
  [InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIDispatch)]
  public interface IEventTarget
  {
    [DispId(-2147417602)]
    void addEventListener(string type, object listener, bool useCapture);
    [DispId(-2147417600)]
    bool dispatchEvent(IDOMEvent evt);
    [DispId(-2147417601)]
    void removeEventListener(string type, object listener, bool useCapture);
  }

  [TypeLibType(4160)]
  [Guid("305104BA-98B5-11CF-BB82-00AA00BDCE0B")]
  [InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIDispatch)]
  public interface IDOMEvent
  {
    [DispId(1001)]
    bool bubbles { get; }
    [DispId(1002)]
    bool cancelable { get; }
    [DispId(1014)]
    bool cancelBubble { get; set; }
    [DispId(1003)]
    IEventTarget currentTarget { get; }
    [DispId(1004)]
    bool defaultPrevented { get; }
    [DispId(1005)]
    ushort eventPhase { get; }
    [DispId(1013)]
    bool isTrusted { get; }
    [DispId(1015)]
    IHTMLElement srcElement { get; }
    [DispId(1006)]
    IEventTarget target { get; }
    [DispId(1007)]
    ulong timeStamp { get; }
    [DispId(1008)]
    string type { get; }

    [DispId(1009)]
    void initEvent(string eventType, bool canBubble, bool cancelable);
    [DispId(1010)]
    void preventDefault();
    [DispId(1012)]
    void stopImmediatePropagation();
    [DispId(1011)]
    void stopPropagation();
  }

 Does anybody face the same difficulties? 
 Any ideas? Thanks so much!

 Claude