把输入数据改为6，为什么训练到39个风机会报错？

File "/home/zjh/桌面/风力发电/train.py", line 122, in
    traverse_wind_farm(train_and_val, settings, cur_setup)
  File "/home/zjh/桌面/风力发电/common.py", line 263, in traverse_wind_farm
    method(exp, model_path, is_debug=params["is_debug"])
  File "/home/zjh/桌面/风力发电/train.py", line 62, in train_and_val
    val_data, val_loader = experiment.get_data(flag='val')
  File "/home/zjh/桌面/风力发电/common.py", line 183, in get_data
    drop_last=drop_last
  File "/home/zjh/桌面/风力发电/venv/lib/python3.7/site-packages/paddle/fluid/reader.py", line 402, in __init__
    drop_last=drop_last)
  File "/home/zjh/桌面/风力发电/venv/lib/python3.7/site-packages/paddle/fluid/dataloader/batch_sampler.py", line 125, in __init__
    self.sampler = RandomSampler(dataset)
  File "/home/zjh/桌面/风力发电/venv/lib/python3.7/site-packages/paddle/fluid/dataloader/sampler.py", line 209, in __init__
    if not isinstance(self.num_samples, int) or self.num_samples <= 0:
  File "/home/zjh/桌面/风力发电/venv/lib/python3.7/site-packages/paddle/fluid/dataloader/sampler.py", line 216, in num_samples
    return len(self.data_source)
ValueError: __len__() should return >= 0