Trying to build an interference checker graph

Hello.

I’m trying to run a quick interference checker graph in a project I’m working on, this is what I got so far. I’m aiming to check for interference between pipes of various systems, (i.e. Domestic Water Piping vs. Sanitary Piping) so I’m selecting the pipes, sorting the by their system classification parameter, and the trying to evaluate them using the Bimorph Element Intersect node.

But all I have achieved to get from the graph is a bunch of empty lists, as you can see in the attached image. I know there are several pipes clashing in these categories Do you have any suggestions or is there something I’m no doing right?

Thanks for the help

Try flattening your lists before connecting them to the Bimorph node.

That actually helped. Thanks