Command getnextnetnodeoutport

I tried to use the function getnextnetnodeoutport to determine the next network node between two different networknodes (attached model). However, in my example the command returns something different?? On arrival of NN1 I try to use the function. Is it correctly called?

The getnextnetnode does give me the next node reference, so I've solved it by writing a little user command to get the outputnumber. But, I would like to use the getnextnetnodeoutport command.

Thanks,
Martijn

P.S. I did not found a topic on commands, so I've put the thread in the user commands.