LightGBMError: Label 754 is not less than the number of label mappings (31).

I am training LAMBDA MART in listwise dataset of Letor collection, this dataset contains 64 features.

How can i resolve it?

Can anyone please help me?

# Create LightGBM dataset
            group = create_group(result['query_id'])
            train_data = lgb.Dataset(result.drop(['relevance', 'query_id'], axis=1), label=result['relevance'], group=group)

            # Parameters for the LambdaMART model
            params = {
                'objective': 'lambdarank',
                'metric': 'ndcg',
                'learning_rate': 0.05,
                'num_leaves': 31,
                'min_data_in_leaf': 20,
                'lambda_l1': 0.1,
                'lambda_l2': 0.1,
                'max_bin': 255,
                'num_iterations': 100,
                'ndcg_eval_at': [1, 3, 5]
            }


           # Train the LambdaMART model
            ranker = lgb.train(params, train_data)