  We demonstrate that the structure of confinement resonances in the
photoionization cross section of an endohedral atom is very sensitive to the
mean displacement <a> of the atom from the cage center. The resonances are
strongly suppressed if 2<a> exceeds the photoelectron half-wavelength. We
explain the results of recent experiments which contradict the earlier
theoretical predictions on the existence of confinement resonances in
particular endohedral systems.
