Vector meson propagator and baryon current conservation

If baryons couple only with ω-mesons, one found the baryon spectral function may be negative. We show this unacceptable result is caused by the kμkν-terms in the ω-meson propagator. Their contribution may not vanish in approximate calculations which violate the baryon current conservation. A rule is suggested, by which the calculated baryon spectral function is well behaved.