  We demonstrate that the collinear expansion fails in the case of gluon
emission from a fast quark produced in $eA$ DIS. In this approximation the N=1
rescattering contribution to the gluon spectrum vanishes. We show that the
higher-twist approach by Guo, Wang and Zhang [4,5] based on the collinear
expansion is wrong. The nonzero gluon spectrum obtained in [4,5] is a
consequence of unjustified neglecting some important terms in the collinear
expansion.
