I am trying to send app-generated request using either JS SDK or graph API but I am not successful and desperate. Issue is that when I am sending request to currently logged user, everything is ok, but when I try to send to different user (even this user already authorized my app) I receive OAuth exception "#2 User can't send this request: Unknown error", sometimes "Failed to send any app requests".
My app has Request 2.0 enabled and is authorized with publish_stream, read_stream and user_about_me permissions. Same error messages I described are shown even in Graph API explorer.
Exactly same issue is described here using JS SDK: Sending an App Generated Request with the JavaScript SDK
... and here using Graph API: Posting app generated apprequest to other facebook users in Java
Please help.