Empty chain when generate depletion chain

Hi everyone, I encountered a problem when I generated the depletion chain with ENDF-B-VIII database. I got an empty chain. Could anybody tell me what mistake I made?

The correct way to call the from_endf method is as follows:

chain = openmc.deplete.Chain.from_endf(decay_files=decay_files, ...)

Wow, it looks like I made a rudimentary mistake about Python. Thank you very much for your answer.