LIMIT, SINCE and UNTIL parameters in page feed

I'm trying to get the news feed of page (I'm admin of that page) using the limit, since and until parameters, but it doesn't work, it doesn't work even in graph api explorer tool. I'm requesting the following:

$fb->api("/PAGE_ID/feed?limit=100")

but it always returns me the last 25 posts, the since and until parameters don't work also. What's the wrong in my code?

Thanks in advance.