  The scattering amplitude for the longitudinal weak bosons is investigated in
the SU(3) gauge-Higgs unification as a function of the scattering energy, the
Wilson line phase \theta_H and the warp factor. The \theta_H-dependence of the
amplitude is quite different in the flat and the warped spacetimes. Generically
the amplitude is enhanced for \theta_H=O(1) in the warped case while it is
almost independent of \theta_H in the flat case. This indicates the tree-level
unitarity is violated in the warped case at a lower scale than that in the flat
case.
