divide surface to panel with the established sizes(single precision)

Hi all,
I have same problem with isotrim component. I am trying to divide a three surface(planar, not flat one direction and not flat two direction surfaces). When I am checking output data dimensions something is wrong with not flat one direction and not flat two direction surfaces. When I am trying to use plugin Paneling tools I have some problem with precision too. Please explain to me where the mistake. No problem only with planar surface.