I am using fedora 18 with Gnome 3.6.2 and I've updated empathy to the latest version (Empathy 3.6.4) yesterday. it works fine at first, but after a while, the notification bar which is at the down part of the screen disappears and no notifications will be shown there anymore. so for new conversations, I hear the sound notification for the message which is received, but because no pop up window is shown, I can't find out who has sent the message and I miss them.
I think the problem is not because of empathy and the main problem is the notification bar which is disappeared. How can I solve this problem?