请问这个是eval阶段gtbbox出现了负值，那这个怎么解决呢？有人知道吗？

Traceback (most recent call last):
File "/home/aistudio/work/PaddleDetection/static/tools/eval.py", line 206, in
main()
File "/home/aistudio/work/PaddleDetection/static/tools/eval.py", line 188, in main
save_only=save_only)
File "/home/aistudio/work/PaddleDetection/static/ppdet/utils/eval_utils.py", line 267, in eval_results
map_type=map_type)
File "/home/aistudio/work/PaddleDetection/static/ppdet/utils/voc_eval.py", line 71, in bbox_eval
gt_boxes = t['gt_bbox'][0].log()
KeyError: 'gt_bbox'