  We analyze the results of a paper on ``Relativistic quantum dynamics of a
charged particle in cosmic string spacetime in the presence of magnetic field
and scalar potential''. We show that the authors did not obtain the spectrum of
the eigenvalue equation but only one eigenvalue for a specific relationship
between model parameters. In particular, the existence of allowed cyclotron
frequencies conjectured by the authors is a mere artifact of the truncation
condition used to obtain exact solutions to the radial eigenvalue equation.
