Meet errors when using Naive method on generated benchmark

I generated a benchmark with "class_incremental_benchmark". But 'Naive' strategy cannot be applied to this benchmark. Can you pls give me some advice?

Code as follows:

datadir = default_dataset_location('mnist')
train_MNIST = as_classification_dataset(MNIST(datadir, train=True, download=True))
test_MNIST = as_classification_dataset(MNIST(datadir, train=False, download=True))
scenario = class_incremental_benchmark({'train': train_MNIST, 'test': test_MNIST}, num_experiences=5)

n_classes = 10
model = SimpleMLP(num_classes=n_classes)

cl_strategy = Naive(
model, SGD(model.parameters(), lr=0.001, momentum=0.9),
CrossEntropyLoss(), train_mb_size=500, train_epochs=1, eval_mb_size=100,
)

print('Starting experiment...')
results = []
for experience in scenario.train_stream:
print("Start of experience: ", experience.current_experience)
print("Current Classes: ", experience.classes_in_this_experience)

# train returns a dictionary which contains all the metric values
print(experience)
res = cl_strategy.train(experience)
print('Training completed')

print('Computing accuracy on the whole test set')
# test also returns a dictionary which contains all the metric values
results.append(cl_strategy.eval(scenario.test_stream))

error as follows:
Traceback (most recent call last):
File "main.py", line 71, in
res = cl_strategy.train(experience)
File "/home/yuanxun/CL/avalanche/avalanche/training/templates/base_sgd.py", line 211, in train
super().train(experiences, eval_streams, **kwargs)
File "/home/yuanxun/CL/avalanche/avalanche/training/templates/base.py", line 162, in train
self._before_training_exp(**kwargs)
File "/home/yuanxun/CL/avalanche/avalanche/training/templates/base_sgd.py", line 291, in _before_training_exp
self.make_train_dataloader(**kwargs)
File "/home/yuanxun/CL/avalanche/avalanche/training/templates/base_sgd.py", line 456, in make_train_dataloader
self.dataloader = TaskBalancedDataLoader(
File "/home/yuanxun/CL/avalanche/avalanche/benchmarks/utils/data_loader.py", line 404, in __init__
task_labels_field = getattr(data, "targets_task_labels")
AttributeError: 'ClassificationDataset' object has no attribute 'targets_task_labels'