cannot download all fits file by Fido.fetch( )

[kako lelouch]

Hello everybody, I have problem when downloading fits files. Here is my code 

from sunpy.net import Fido, attrs

attrs_time = attrs.Time('2017/10/08 10:00', '2017/10/08 11:00')

result = Fido.search(attrs_time, attrs.Instrument('aia'),

                     attrs.Wavelength(211*u.angstrom),

                     attrs.vso.Sample(5*u.minute))

print("{} files found.".format(result.file_num))

filenames = Fido.fetch(result, path=path, wait=True)

print("{} files downloaded.".format(len(filenames)))

and here is the output

12 files found.
[                                        ========================================
3 files downloaded.

It seems that I never succeed in downloading all fits files, always part of them. I think it is not due to the network issue, because this happens also when I am using servers in our observatory.

Thank you for your attention to this matter.