KeyError: 1, when using only 1 class dataset to evaluation

[YipChakwai]

When I use my own dataset(only 1 class) to evaluation, I got the following error. I'd appreciate it if you could guide me.

Traceback (most recent call last):
File "G:/SparseR-CNN-main/projects/SparseRCNN/train_net.py", line 176, in
launch(
File "G:\SparseR-CNN-main\detectron2\engine\launch.py", line 66, in launch
main_func(*args)
File "G:/Code+paper/SparseR-CNN-main/projects/SparseRCNN/train_net.py", line 170, in main
return trainer.train()
File "G:\SparseR-CNN-main\detectron2\engine\defaults.py", line 421, in train
super().train(self.start_iter, self.max_iter)
File "G:\SparseR-CNN-main\detectron2\engine\train_loop.py", line 144, in train
self.after_train()
File "G:\SparseR-CNN-main\detectron2\engine\train_loop.py", line 153, in after_train
h.after_train()
File "G:\SparseR-CNN-main\detectron2\engine\hooks.py", line 361, in after_train
self._do_eval()
File "G:\SparseR-CNN-main\detectron2\engine\hooks.py", line 331, in _do_eval
results = self._func()
File "G:\SparseR-CNN-main\detectron2\engine\defaults.py", line 374, in test_and_save_results
self._last_eval_results = self.test(self.cfg, self.model)
File "G:\SparseR-CNN-main\detectron2\engine\defaults.py", line 542, in test
results_i = inference_on_dataset(model, data_loader, evaluator)
File "G:\SparseR-CNN-main\detectron2\evaluation\evaluator.py", line 176, in inference_on_dataset
results = evaluator.evaluate()
File "G:\SparseR-CNN-main\detectron2\evaluation\coco_evaluation.py", line 173, in evaluate
self._eval_predictions(predictions, img_ids=img_ids)
File "G:\SparseR-CNN-main\detectron2\evaluation\coco_evaluation.py", line 212, in _eval_predictions
result["category_id"] = reverse_id_mapping[category_id]
KeyError: 1