Subsurface is invalid because the trimming U-domain is singular

Hello, I’ve been trying to resolve a problem with an example in Grasshopper primer manual, the excersice it’s called Uneven Surface Diagrid. I have a problem with U domain in the Isotrim componet, I think something is wrong with the Graph Mapper component. If someone know how to resolve it, I would be very gratefult if you could explain to me what’s wrong. I’m leaving the files here, so anyone can check it out.

Thank you in advance guys.[ (11.8 KB) Uneven_surface_diagrid.3dm (26.8 KB) ](http://)

It seems you forgot to reparameterize your surface at the beginning. (12.0 KB)


Thank you so much!!