when I try to python train.py, test sets with lfw data sets ,error

[molyswu]

Traceback (most recent call last):
File "train.py", line 542, in
main(parse_arguments(sys.argv[1:]))
File "train.py", line 213, in main
label_batch, lfw_paths, actual_issame, args.lfw_batch_size, args.lfw_nrof_folds, log_dir, step, summary_writer,best_accuracy,saver_save,model_dir,subdir)
File "train.py", line 313, in evaluate
_, _, accuracy, val, val_std, far = lfw.evaluate(emb_array, actual_issame, nrof_folds=nrof_folds)
File "/home/yjzx/Downloads/Additive-Margin-Softmax/lfw.py", line 43, in evaluate
np.asarray(actual_issame), 1e-3, nrof_folds=nrof_folds)
File "/home/yjzx/Downloads/Additive-Margin-Softmax/facenet.py", line 566, in calculate_val
val[fold_idx], far[fold_idx] = calculate_val_far(threshold, dist[test_set], actual_issame[test_set])
File "/home/yjzx/Downloads/Additive-Margin-Softmax/facenet.py", line 580, in calculate_val_far
val = float(true_accept) / float(n_same)
far = float(false_accept) / float(n_diff)
ZeroDivisionError: float division by zero