On page 2, the sentence "The determinant line bundle .... determines a projective embedding" seems to imply that the determinant line bundle is very ample, which is false in general without taking tensor powers, see F. Gavioli, Internat. J. Math. {\bf 15} (2004), no.~3, 259--287; MR2060790 (2005f:14072). The sentence should read "The space of sections of the pre-quantum line bundle over R_K(X,\mu_1,\ldots,\mu_b) is isomorphic to the space of genus zero conformal blocks ....". The error does not affect the statement or proof of any of the results in the paper.