Finished loading image paths

请问这个错误是怎么造成的，我见了一下train.csv,bing没有发现错误，希望有大佬能帮我解读一下

[10/22 10:46:15][INFO] ava_helper.py: 62: Finished loading image paths from: /home/zjy/Desktop/Project/SlowFast/data/USER_AVA/frame_lists/train.csv
Traceback (most recent call last):
File "/home/zjy/Desktop/Project/SlowFast/tools/run_net.py", line 52, in
main()
File "/home/zjy/Desktop/Project/SlowFast/tools/run_net.py", line 27, in main
launch_job(cfg=cfg, init_method=args.init_method, func=train)
File "/home/zjy/Desktop/Project/SlowFast/slowfast/utils/misc.py", line 430, in launch_job
func(cfg=cfg)
File "/home/zjy/Desktop/Project/SlowFast/tools/train_net.py", line 597, in train
train_loader = loader.construct_loader(cfg, "train")
File "/home/zjy/Desktop/Project/SlowFast/slowfast/datasets/loader.py", line 114, in construct_loader
dataset = build_dataset(dataset_name, cfg, split)
File "/home/zjy/Desktop/Project/SlowFast/slowfast/datasets/build.py", line 31, in build_dataset
return DATASET_REGISTRY.get(name)(cfg, split)
File "/home/zjy/Desktop/Project/SlowFast/slowfast/datasets/ava_dataset.py", line 47, in __init__
self._load_data(cfg)
File "/home/zjy/Desktop/Project/SlowFast/slowfast/datasets/ava_dataset.py", line 63, in _load_data
boxes_and_labels = ava_helper.load_boxes_and_labels(
File "/home/zjy/Desktop/Project/SlowFast/slowfast/datasets/ava_helper.py", line 101, in load_boxes_and_labels
all_boxes, count, unique_box_count = parse_bboxes_file(
File "/home/zjy/Desktop/Project/SlowFast/slowfast/datasets/ava_helper.py", line 222, in parse_bboxes_file
if box_key not in all_boxes[video_name][frame_sec]:
KeyError: 2