Pytest - Testing dataset with pandas

HI I need to test and validate the columns from an excel file with Pandas and Pytest

Here is my code

  import pytest
  import pandas as pd
  import datatest as dt

  @pytest.fixture(scope='module')
   def df():
        if os.path.exists(f"test_data/example_pricing.xlsx"):
             with open(f"test_data/example_pricing.xlsx", "rb") as f:
                   excel_data_df = pd.read_excel(f"test_data/example_pricing.xlsx", sheet_name='CustomerPricing',
                    usecols=lambda c: not c.startswith('Unnamed:'))

                   return excel_data_df


   @pytest.mark,mandatory
   def test_columns(df):
       dt.validate(df.columns,{'Age'},) # Age here is a column in excel file

But I got validationError, unable to pass the test

FAILED tests/unit/tests.py::test_columns - datatest.ValidationError: does not satisfy set membership (18 differences): [

Any ideas how to validate columns from excel using pandas ?