Feedback API not working

I tried retrieving the feedback of a specific forum. This is not working. I was able to get other information from the API (user information, types from forums). 

My url is constructed as following:

https://userecho.com/api/forums/[Forum ID]/feedback.json?access_token=[KEY]&limit=0

Also just now I tried retrieving post/comment information from a specific user and got the following error:

Piston/0.2.2 (Django 1.4.2) crash report: Traceback (most recent call last): File "./ue_api/handlers.py", line 481, in read raise OAuthError('Not enought rights.') OAuthError

Could you look into this?

Thanks in advance.