Can list all keys using h5py but not with hdfstore

Question

I would like to use pandas to read hdf5 files. But unfortunately I can not get it to work. Using VS-code Jupiternotebook on Windows:

This does not list anything and gives no error:

import pandas as pd
with pd.HDFStore('D:/sample.h5' ) as f:
    print(list(f.keys()))
    pass

The output here is : nothing

Same file but using h5py works fine:

import h5py
with h5py.File('D:/sample.h5, 'r') as f:
   print(list(f.keys()))
   pass

The output here is : ['INDEX', 'NASTRAN']

I do not know in which way the file was created.

Any ideas?