  In a recent paper, \cite{deguchi}, Deguchi and Fujiwara claim that our
results in \cite{BGR} are wrong, and compute what they claim is the square
integrable vacuum of their annihilation operators. In this brief note, we show
that their vacuum is indeed not a vacuum, and we try to explain what is behind
their mistake. We also consider a very simple example clarifying the core of
the problem.
