  In a recent paper [Phys.Rev.Lett. 82, 3665 (1999)], magnetic field driven
spin transitions in fractional quantum Hall (FQH) states were reported, and in
particular, at filling factors 2/3 and 2/5, weak features were observed at half
polarization. This would imply that the ground state energy is non-monotonic at
half polarization. It was proposed in
  Ref.[Phys. Rev. Lett. 84, 350 (2000)] that the system is then a charge
density wave (CDW) state of composite fermions with a subband gap that could
explain the observed plateaus at half polarization. Similar CDW state is also
expected at filling factor 2/3. Here we show that the proposed CDW state is not
the half polirized ground state at these two filling factors.
