Nikolay,
Thanks for the information and the fix. I tried this again today, and I noticed that all of the calls to extract an operator matrix (that previously raised an error), now actually show a matrix.
I guess that, based on your explanation concerning missing arguments being the culprit, that you have now put in some placeholder arguments (in case the user does not specify any)?
That makes sense to me, but I just want to make sure that I understand what you did.
Thanks :<)
Mike