Comment on: “Solution of the Dirac equation for the Woods–Saxon potential with spin and pseudospin symmetry” [Phys. Lett. A 338 (2005) 90]

The bound-state method employed by Guo and Sheng [J.Y. Guo, Z.-Q. Sheng, Phys. Lett. A 338 (2005) 90] is shown inadequate since only one of their solutions remains compatible, in the spin-symmetric low-mass regime, with the physical boundary conditions. We clarify the problem and construct a new, correct solution in the pseudospin-symmetric regime.