Hi. I created lmdb dataset on my own data by running create_lmdb_dataset.py. then I run the train command on it and got the following output:

CUDA_VISIBLE_DEVICES=0 python3 train.py --train_data result/train --valid_data result/test --Transformation TPS --FeatureExtraction ResNet --SequenceModeling BiLSTM --Prediction Attn

dataset_root: result/train
opt.select_data: ['MJ', 'ST']
opt.batch_ratio: ['0.5', '0.5']

dataset_root: result/train dataset: MJ
Traceback (most recent call last):
File "train.py", line 283, in
train(opt)
File "train.py", line 26, in train
train_dataset = Batch_Balanced_Dataset(opt)
File "/home/mor-ai/Work/deep-text-recognition-benchmark/dataset.py", line 37, in init
_dataset = hierarchical_dataset(root=opt.train_data, opt=opt, select_data=[selected_d])
File "/home/mor-ai/Work/deep-text-recognition-benchmark/dataset.py", line 106, in hierarchical_dataset
concatenated_dataset = ConcatDataset(dataset_list)
File "/home/mor-ai/.local/lib/python3.6/site-packages/torch/utils/data/dataset.py", line 187, in init
assert len(datasets) > 0, 'datasets should not be an empty iterable'
AssertionError: datasets should not be an empty iterable

Can you help me resolve this?