missing data from the api

[Elad Hershkovitz]

Hello, 

I'm working on an api integration trying to pull some general data from the api. 
While I was successfully able to get data from the schools, staff and students 
I'm not able to get data around gradebooks and classes. The api returns empty array for all which seems incorrect. 

I was wondering if I'm missing any permissions or something else that may cause the api to return empty results. 

Thanks !