In [19] the author proved that any hypersurface with at most three distinct principal curvatures in space
forms has constant mean curvature. Recently, we found out that the proof given in
[19] has a gap which we fill in the present paper. More specifically, in
order to overcome this problem,
we introduce a new method involving algebraic tools and Mathematica programming. We manage to find all
cases that the original proof missed and show that all hypersurfaces of this type still have constant mean curvature.