Although Peng Yafei and his co-workers discovered some faults with the pseudo-stress function method suggested by Y. S. Lee in 1987, the authors did not provide convincing arguments. We investigate the crucial assumption in Lee’s method by rewriting it as the form of real part and imaginary part. Through a specific counterexample, we point out that the crucial assumption in Lee’s theory is untenable. Namely, for given Airy’s stress function, it cannot be guaranteed that the pseudo-stress function Λ(x,y) exists. The root cause of the fault with Lee’s method is found in this paper.