Facebook OAuth redirect_uri to page tab error

For me the problem was the GET request, somehow it seems facebook asks for the GET parameter, I will show you what I mean:

I had this:

uri = "http://www.facebook.com/pagename/app_appId";

When I changed it to the below it started working:

uri = "http://www.facebook.com/pagename/?sk=app_appId";

Hope this helps someone as it helped me.