Network Surface behaving weird

Hello everybody!
I am having this weird problem not being able to create network surface from 4 curves. The curves are connected it seems. The weird part is, if I bake these curves and then set them with crv components, it works.
Network srf component says: At least two curves are needed in the U direction.
I am attaching screenshots and gh. file of the script.
Thank you for your attention and help!

NETWORK_SURFACE.gh (30.5 KB)

Just flattern the inputs.

thank you so much @Quan_Li! Such a simple fix..