Does GET /:urlname/events/:id/attendance Work?

[Michael Allen Smith]

Using PHP I am successfully able to access:

GET /:urlname/events/:id/

However, when I try to access Attendance via  /:urlname/events/:id/attendance - I get this error:

{"errors":[{"code":"authorization_error","message":"you are not authorized to view attendance"}]}

Both calls have the KEY and &sign=true. Why does the first work, but not the attendance?

WORKS: https://api.meetup.com/seattle-coffee-club/events/245430581?key=__MY_KEY__&sign=true (returns data)

FAILS: https://api.meetup.com/seattle-coffee-club/events/245430581/attendance?key=__MY_KEY__&sign=true (returns error)