Using custom dataset fails with error None type object

Hello, I am trying to execute vectordbbench with a custom dataset. For ease of use, I have used the openAI50k dataset parquet files that were downloaded from a previous run into from the /var/vectordb_bench/datasets.
When i execute this : vectordbbench pgvectorhnsw --config-file custom_config.yml it throws the following error:

INFO: INIT_SEARCH_RUNNER (task_runner.py:259) (3057207)
WARNING: test_data None (task_runner.py:260) (3057207)
WARNING: Failed to run performance case, reason = 'NoneType' object has no attribute 'columns' (task_runner.py:192) (3057207)
Traceback (most recent call last):
  File "/home/VectorDBBench/vectordb_bench/backend/task_runner.py", line 179, in _run_perf_case
    self._init_search_runner()
  File "/home/VectorDBBench/vectordb_bench/backend/task_runner.py", line 261, in _init_search_runner
    log.info(f"test_data {self.ca.dataset.test_data.columns}")
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'columns'

How do I go ahead and use the custom dataset?