  Recently, Carlip proposed a derivation of the entropy of the two-dimensional
dilatonic black hole by investigating the Virasoro algebra associated with a
newly introduced near-horizon conformal symmetry. We point out not only that
the algebra of these conformal transformations is not well defined on the
horizon, but also that the correct use of the eigenvalue of the operator $L_0$
yields vanishing entropy. It has been shown that these problems can be resolved
by choosing a different basis of the conformal transformations which is regular
even at the horizon. We also show the generalization of Carlip's derivation to
any higher dimensional case in pure Einstein gravity. The entropy obtained is
proportional to the area of the event horizon, but it also depends linearly on
the product of the surface gravity and the parameter length of a horizon
segment in consideration. We finally point out that this derivation of black
hole entropy is quite different from the ones proposed so far, and several
features of this method and some open issues are also discussed.
