BitBucket API: Forbidden when filtering foreign repositories

Some facts:

• I'm using OAuth to authenticate the requests.
• I'm using Zend-OAuth as Http-Client

Now the problem:
I load issues from my repos via this url:
https://bitbucket.org/api/1.0/repositories/OWNER/SLUG/issues/\\
Everything works fine.

Now I want to filter the Issues by responsible person:
https://bitbucket.org/api/1.0/repositories/OWNER/SLUG/issues?responsible=NAME

This does only work with repositories created by me. With others I get a Forbidden-Error.
The problem occurs if I set other filters or options(like limit or start), too.

I entered the API-Url into a web browser and there this is working.