I am having an issue with a definition. I am trying to get the curve elements of a ceiling to create model lines. If a shaft or other opening is in the ceiling however, I get an error when trying to create a polycurve. I am trying to fix this by using a while loop to take each individual curve and join them until they form a closed curve. However, I cannot get the definition to give me a valid polycurve. Attached is a picture of my definition, does anyone know why this is not working?