To my knowledge, the first point of the curve must be the yield point, that is, zero plastic strain and yield stress (i.e. plastic strain=0, stress=260 Mpa).

Thanks! it worked!

ANSYS treat the linear elastic and plastic regime "separately". You can't define the whole stress-strain curve in non of the plasticity approatche.s For that reason if you want to define a multilinear kinematic hardening plasticity the first point has to be zero strain and stress corresponds to Yield strength.