Deletion of constraints dosn't work

[Buchholz Matthias]

Hi,

am currently writing an Addin for EA 6.5 in C#. When i call the deleteAt or Delete Method of the Collection Class, with Constraints in it,  a Exception with no   Errormessage or similar usefull occurs.
I used much the same code to delete Files oder Scenarios from a Collection, but there the code works.
The Exception is thrown independant of using it in or outside the loop over a collection.

I hope somebody know what to do.

Best regards

Matthias