Not able to separate points

I am trying to make uniform horizontal line between vertical line after dividing them, all in grasshopper, but when I take out a set of points using item list component, the points don’t seem to want to enter into the polyline component and just shows up an error, any solutions are welcome

you seem to have an issue when to flatten and when to graft.

Please upload .gh file so we can see the details .

the grasshopper file for the same

eco resrt form.gh (12.9 K)

The curve is not internalized.
One can only imagine.

what does that mean, can you please explain more

It seems pretty clear to me.

eco resrt form a.gh (18.7 KB)

thank you so much, i didn’t know it used matrix order to view the numbers