Is NIP57 still the best way to determine the amount of zaps a note has? I'm not getting reliable results searching for Kind 9735 events that have 'e' tags to my target event.

I'm using 'pynostr' library for python:
zappers = getevent(kinds=[9735], event_refs=['f49c4364445f1c780b8fecae595a7d4ba390df66dceaeaad063c0f235103f155'])

Am I missing something?
 nostr:npub137c5pd8gmhhe0njtsgwjgunc5xjr2vmzvglkgqs5sjeh972gqqxqjak37w  nostr:npub1vp8fdcyejd4pqjyrjk9sgz68vuhq7pyvnzk8j0ehlljvwgp8n6eqsrnpsw  nostr:npub1nxa4tywfz9nqp7z9zp7nr7d4nchhclsf58lcqt5y782rmf2hefjquaa6q8