Error while calling Trainer.Fit()

I am trying to train a CNN Model. While calling the trainer.fit method, it throws out the following error:

  File "/home/*redacted*/miniconda3/envs/torch-lightning/lib/python3.8/site-packages/pytorch_lightning/trainer/trainer.py", line 553, in fit
    self._run(model)
  File "/home/*redacted*/miniconda3/envs/torch-lightning/lib/python3.8/site-packages/pytorch_lightning/trainer/trainer.py", line 850, in _run
    self.config_validator.verify_loop_configurations(model)
  File "/home/*redacted*/miniconda3/envs/torch-lightning/lib/python3.8/site-packages/pytorch_lightning/trainer/configuration_validator.py", line 34, in verify_loop_configurations
    self.__verify_train_loop_configuration(model)
  File "/home/*redacted*/miniconda3/envs/torch-lightning/lib/python3.8/site-packages/pytorch_lightning/trainer/configuration_validator.py", line 49, in __verify_train_loop_configuration
    has_training_step = is_overridden("training_step", model)
  File "/home/ashim/miniconda3/envs/torch-lightning/lib/python3.8/site-packages/pytorch_lightning/utilities/model_helpers.py", line 45, in is_overridden
    raise ValueError("Expected a parent")

There is no additional information except this. Can anyone suggest how I can go about the debugging process?

Seems like I forgot to inherit pl.LightningModule while declaring the model class. Weird that there are no relevant results for this.