3D Voronoi with qhull plugin - problem

Hi,

I want to create a voronoi 3D structure with qhull from points created in Rhino (not randomly), I think I read everything possible and ok, this is working usually. But sometimes, I do not know why, it refuses to make my request. For example like in attachment:  I have there approximately two rows of points and when I choose one of them (doesn't matter which one) it works but if I choose both at the same time it tells me that input string was not in correct format and shows the line 0 (like in attachment). Some points are freely situated and some are in pairs - like with the same x and z coordinates but different y. But with another points it works when they have just different z coordinate so I do not think it is a problem. I have no duplicated points, I have cleaned Grasshopper path just to two buttons and I have no idea what can go wrong.

I would be really grateful for any help. I try to solve it for two weeks and really can not find the solution.