  The spin-dependent electron transport has been studied in magnetic
semiconductor waveguides (nanowires) in the helical magnetic field. We have
shown that -- apart from the known conductance dip located at the magnetic
field equal to the helical-field amplitude $B_h$ -- the additional conductance
dips (with zero conductance) appear at magnetic field different from $B_h$.
This effect occuring in the non-adiabatic regime is explained as resulting from
the resonant Landau-Zener transitions between the spin-splitted subbands.
