  A relation among the form factors of $<D \mid A_\mu \mid D^*>$ at $q^2 \to 0$
is derived. It is verified to lowest order in both the $1/m_c$ expansion and
the expansion in number of derivatives using the effective lagrangian that
incorporates the heavy quark symmetries for the b and c quarks, and the chiral
symmetry for the u, d, s quarks.
