Hello. Thanks to you I found the problem! Im using milimeters as my units. If I type the height of stairs as 2800mm it works fine but then once I enter set parameters it shows calculated rise as some weird number (see attachment). If that number is set then we get errors in Ruby console. To fix the problem I need to change that strange number of Rise to regular number - say 180 - then change other parameters and then its possible to save. Just need to adjust the height of stairs afterwards Thank You! [image: LPP5_Adnotacja2020-03-20152406.jpg]