Comment on `Five-Dimensional Cosmological Model with Variable

This comment corrects the small errors in the Letter of Baysal and Yilmaz Chin. Phys. Lett. 24(2007)2185, where the case of n=1 was ignored. Meanwhile, the discussion in this comment on the case of n=-3 is novel, which
shows a potential reason why today the effect of the extra dimension has not been observed.