have you checked in the device manager to make sure it is in fact working and enabled. Some AC97's used to conflict with other devices.
I just got you boards manual, there is no mention of ac97 anywhere other then the bios option you have on. So no need to go jumper searching.
Check the device manager and post if you see anything out of the ordinary.
X's mean the device is turned off by windows or the user. the ! means that the wrong driver or no drivers are installed.