  Recently, in Phys. Rev. D 98, 084002 (2018), an investigation was carried out
on the gravitational radiation from binary systems in conformal gravity and
massive conformal gravity. According to the authors of the paper, these two
theories differ only by the sign of a parameter in the matter action of a
general conformal theory. For a negative parameter the general conformal theory
indeed corresponds to conformal gravity. However, here, we argue that for a
positive parameter the general conformal theory does not correspond to massive
conformal gravity.
