This is a comment in response to the claims made in a recent paper by Zhang and Ding [Opt. Express 17, 22235-22239 (2009)]. The authors claimed that an error has been found in a previous paper [Opt. Express 12, 3377-3382 (2004)] and provided a "guess" of how the Poynting vector was calculated. These claims are incorrect and are based on a misconception.