  To justify the origin of anomalous Hall effect (AHE), it is highly desirable
to have the system parameters tuned continuously. By quantitative calculations,
we show that the doping dependent sign reversal in
CuCr$_{2}$Se$_{4-x}$Br$_{x}$, observed but not understood, is nothing but
direct evidence for the Berry-Phase mechanism of AHE. The systematic
calculations well explain the experiment data for the whole doping range where
the impurity scattering rates is changed by several orders with Br
substitution. Further sign change is also predicted, which may be tested by
future experiments.
