  We show that in hard exclusive electroproduction, ep-->eVp, the leading-twist
hard-scattering coefficient for the production of a transversely polarized
vector meson V vanishes to all orders of perturbation theory. This implies that
this process cannot be used to measure the skewed transversity distribution of
quarks in a hadron. In contrast, a recent calculation obtained a non-zero value
at NLO. We show that this calculation is incorrect because it failed to include
the necessary collinear subtractions. Our method of proof also applies to other
processes whose hard-scattering coefficients are constrained by chirality and
helicity conservation, and thus validates helicity selection rules based on
these symmetries.
