MATH > Evaluate and expression error

Hi everyone,

I am opening the discussion because I didn't find anything online about this error.I must admit i am a newbie and this error might be very simple, nevertheless any help will be much appreciated.

I am running daylight analysis for daylight factor and I cant get results.I sued this script 4 or 5 months ago and it wokred properly.I dont now if it is an update or bug problem.

1. Expression generated an error for (x, y): Function Round is undefined for parameters: null & double 

Many thanks,

N