IOPO data error

Traceback (most recent call last):
--
File "/code/llamafactory/launcher.py", line 23, in
launch()
File "/code/llamafactory/launcher.py", line 19, in launch
run_exp()
File "/code/llamafactory/llamafactory/train/tuner.py", line 61, in run_exp
run_iopo(model_args, data_args, training_args, finetuning_args, callbacks)
File "/code/llamafactory/llamafactory/train/iopo/workflow.py", line 44, in run_iopo
dataset_module = get_dataset(model_args, data_args, training_args, stage="iopo", **tokenizer_module)
File "/code/llamafactory/llamafactory/data/loader.py", line 238, in get_dataset
dataset = _get_preprocessed_dataset(
File "/code/llamafactory/llamafactory/data/loader.py", line 175, in _get_preprocessed_dataset
column_names = list(next(iter(dataset)).keys())
StopIteration

i use the trace.json.