Adding a Managed handler fails...

[Luuk]

I am trying to add a 'Managed handler' and receive next message:
(It's in DUTCH, translation below)
'Er is een fout opgetreden tijden de uitvoering van deze bewerking
Details:
Deze methode kan niet worden aangeroepen tijdens de initialisatiefase vóór het starten van de toepassing'

In English something like:
'There has been an error during this action
Details:
This method can not be called during the initialization phase before starting the application

The drop-down box that is shown is empty.
I have installed .NET4.5

Can anyone give a clue?
I was not able to find any working solution so far ...

[Luuk]

The clue was that I did build my application as a 32-bit.
I should not have done that!