Unity Facebook : 400 Bad Request

I using following code to get user data from facebook

IEnumerator UserFBDataGet(string accessTkn)
{
    var  downloader3 = new WWW (  "http://ift.tt/1JLg8Pe"+accessTkn  );
    //Application.OpenURL (  "http://ift.tt/1JLg8Pe"+accessTkn  );
    yield return downloader3;
    print(" downloader3.text  ="+downloader3.text );
    if(downloader3.error == null)
    {
        print(" downloader3.text  ="+downloader3.text );
    }
    else
    {
        print(" downloader3.error  ="+downloader3.error );
    }

}

It showing Error

You are trying to load data from a www stream which had the following error when downloading. 400 Bad Request UnityEngine.WWW:get_text() c__Iterator1:MoveNext() (at Assets/FBDesktopManager.cs:126)

Even i use WWWForm same error is showing

IEnumerator UserFBDataGet(string accessTkn)
{

    userDataGetUrl = "http://ift.tt/P3QvMV?";

    WWWForm  wf = new WWWForm();

    wf.AddField ("fields","id,name,email") ;
    wf.AddField ("access_token",accessTkn) ;

    WWW  downloader3 = new WWW(userDataGetUrl,wf) ;

        yield return downloader3;

    print(" downloader3.text  ="+downloader3.text );
            if(downloader3.error == null)
            {
                print(" downloader3.text  ="+downloader3.text );
            }
            else
            {
                print(" downloader3.error  ="+downloader3.error );
            }


}

But when I call

Application.OpenURL (  "http://ift.tt/1JLg8Pe"+accessTkn  );

in that page i get all data properly.