Nozzle modeling: W41-27 error

I am trying to model a 20" STD connection to a tank of 40 m diameter at 1 m above ground level, filled to 13 m high. Naturally I use the API 650 flexibility method (I assume it's using the Appendix P calculations, meant for tanks above 36 m in diameter), but after entering all the requisite parameters, I get the following error:

Clearly I'm missing something, or I'm misunderstanding an aspect of the Nozzle interface. Can anyone please explain what I'm doing wrong? I have entered the following values:

Thanks so much!