XMPPError: not-authorized - auth android

Question

i want to send a chat message to group. But i am not able to join that particular room from android application, i am using openfire.. every time i am getting

XMPPError: not-authorized

auth error when i am trying to join the room.. Please response.. Following are the code:

MultiUserChatManager manager = MultiUserChatManager.getInstanceFor(connection);
MultiUserChat muc2 = manager.getMultiUserChat("[email protected]");
            try {
                muc2.join(fromName);
            }
            catch (Exception e){
                e.printStackTrace();
            }