I was almost going to post saying I had the same problem but I just figured it out.
The ID is not the name of the photoset. When you open a photoset in your browser, look at the URL and you'll see a long number at the end of it--that's the ID.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Logged In: YES
user_id=1250646
Originator: NO
I was almost going to post saying I had the same problem but I just figured it out.
The ID is not the name of the photoset. When you open a photoset in your browser, look at the URL and you'll see a long number at the end of it--that's the ID.