"Nothing" was returned? How do you fit "nothing" into a datatype of 'N'? And "didn't work" does not say anything about was was or wasn't returned or what was or wasn't written to STDERR. So "nothing was returned with no error message" is certainly tons better than "didn't work", despite the first half of it being inaccurate.

I don't see your code trying to print an eror message so I'm not at all surprised that no error message was printed. You might want to read up on the API you are using to figure out how it reports errors so that you can add error message(s) to your code. It is certainly quite unusual for a useful programming API to simply write information to STDERR when you use the API wrong. Useful APIs tend to report error information to the caller (in ways that you have to read the documentation or even the code to determine accurately) so that the calling code can decide whether it should pass that on to the user (and how it should be passed on to the user) or whether the failure should be dealt with some other way.

Also, D is double, and that's what I had.

Your node had 'N' and the node that you said you tried had 'N', so if you had 'D', then your problem report was even worse.