Erratum for "Nucleosynthesis Constraints on Active-Sterile..."

The magnetization asymmetry given in eq. 3.6 of the above paper (ref. [1], hep-ph/9402332) has a wrong relative sign between particle and anti-particle contributions. Here we present the derivation of the correct sign and its implications for the limits derived in [1]. This sign has also been recently derived in a paper by Elmfors, Grasso and Raffelt, CERN-TH/96-88 [hep-ph/9605250] (ref. [2]) using a different method. While the sign error in [1] does affect the nucleosynthesis bounds derived in [1], we would like to stress that, in contrast to the criticism made in [2], it does not affect in any way the conclusions reached in subsequent papers in S. Pastor, V. B. Semikoz, J. W. F. Valle, Phys.Lett.B369 (1996) 301 and Astropart. Phys. 3 (1995) 87.